Anti-robo4 antibodies and uses therefor

ABSTRACT

The invention provides anti-Robo4 antibodies, and compositions comprising the antibodies and methods of using these antibodies, including diagnostic and therapeutic methods.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/028,124, filed Feb. 8, 2008, which claims the benefit of U.S.Provisional Patent Applications Nos. 60/889,214, filed Feb. 9, 2007 and60/891,475, filed Feb. 23, 2007, the disclosures of which are herebyincorporated by reference in their entirety for all purposes.

FIELD OF THE INVENTION

The present invention relates generally to the fields of angiogenesis,and endothelial cell proliferation and migration. More specifically, theinvention concerns modulators of Robo4, and uses of such modulators.

BACKGROUND OF THE INVENTION

The Roundabout family of receptors are molecular guidance moleculeswhich regulate axon guidance, neuronal migration and leukocytechemotaxis in response to interaction with Slit proteins (Suchting etal., FASEB J. 19:121-123 (2005)). Roundabout receptor molecules containfive immunoglobulin and three fibronectin domains in their extracellularregion. Magic Roundabout (i.e., Robo4 or endothelial cell-specificmolecule 4 (ESCSM4)) is structurally distinct from other roundaboutfamily members. Human Magic Roundabout (Robo4) comprises twoimmunoglobulin and major histocompatibility complex domains (amino acids46-116 and 151-209), two fibronectin type III domains (amino acids252-335 and 347-432), a transmembrane region (468-490), and a prolinerich region (amino acids 715-772) (see Huminiecki et al., Genomics79(4):547-552 (2002), and FIG. 1 therein). Mouse and human Robo4 show75% nucleotide sequence identity (Huminiecki et al., supra (2002)).

Robo4 expression analysis indicated that Robo4 expression is highlyrestricted, with strong expression in placenta and tumors includingbrain, bladder, and colonic metastasis to the liver, where tumorexpression is restricted to tumor vasculature (Huminiecki et al., supra(2002)). In addition, Robo4 expression is associated with sites ofactive angiogenesis, but is not detected in neuronal tissue (Huminiecki,L. et al., supra (2002)).

As a membrane associated receptor with extracellular domains, Robo4 is auseful target for delivering cytotoxic therapeutics for inhibition ofvascular endothelial cell proliferation during angiogenesis. Robo4 isalso a useful target to delivery of detectable markers to proliferatingvascular endothelial cells. Antibody conjugates targeted to Robo4 (alsoreferred to as ECSM4) have also been reported as potential therapeuticcompounds where the conjugate comprises a cytotoxin and as potentialdiagnostic markers where the conjugate comprises a detectable label(see, for example, WO 2002036771).

The use of antibody-drug conjugates for the local delivery of cytotoxicor cytostatic agents, i.e. drugs to kill or inhibit tumor cells in thetreatment of cancer (Syrigos and Epenetos, Anticancer Res. 19:605-614(1999); Niculescu-Duvaz and Springer, Adv. Drg Del. Rev. 26:151-172(1997); U.S. Pat. No. 4,975,278) allows targeted delivery of the drugmoiety to tumors, and intracellular accumulation of the drugs.

A number of antibody-drug conjugates that target other molecules havebeen or are being developed. For example, ZEVALIN® (ibritumomabtiuxetan, Biogen/Idec) is an antibody-radioisotope conjugate composed ofa murine IgG1 kappa monoclonal antibody directed against the CD20antigen found on the surface of normal and malignant B lymphocytes and¹¹¹In or ⁹⁰Y radioisotope bound by a thiourea linker-chelator (Wisemanet al., Eur. Jour. Nucl. Med. 27(7):766-77 (2000); Wiseman et al. Blood99(12):4336-42 (2002); Witzig et al., J. Clin. Oncol. 20(10):2453-63(2002); Witzig et al., J. Clin. Oncol. 20(15):3262-69 (2002)). AlthoughZEVALIN has activity against B-cell non-Hodgkin's Lymphoma (NHL),administration results in severe and prolonged cytopenias in mostpatients. MYLOTARG™ (gemtuzumab ozogamicin, Wyeth Pharmaceuticals),composed of a huCD33 antibody linked to calicheamicin, was approved in2000 for the treatment of acute myeloid leukemia by injection (Drugs ofthe Future (2000) 25(7):686; U.S. Pat. Nos. 4,970,198; 5,079,233;5,585,089; 5,606,040; 5,693,762; 5,739,116; 5,767,285; 5,773,001).Cantuzumab mertansine (Immunogen, Inc.), composed of a huC242 antibodylinked via the disulfide linker SPP to the maytansinoid drug moiety,DM1, is being developed for the treatment of cancers that express CanAgantigen, such as colon, pancreatic, gastric, and others. MLN-2704(Millennium Pharm., BZL Biologics, Immunogen Inc.), composed of ananti-prostate specific membrane antigen (PSMA) monoclonal antibodylinked to the maytansinoid drug moiety, DM1, is being developed for thepotential treatment of prostate tumors. The same maytansinoid drugmoiety, DM1, was linked through a non-disulfide noncleavable linker,SMCC, to a mouse murine monoclonal antibody, TA.1 (Chari et al., CancerRes. 52:127-131 (1992)). This conjugate was reported to be 200-fold lesspotent than the corresponding disulfide linker conjugate.

The auristatin peptides, auristain E (AE) and monomethylauristatin(MMAE), synthetic analogs of dolastatin, have been conjugated to: (i)cBR96, a chimeric monoclonal antibody specific for Lewis Y oncarcinomas; (ii) cAC10 which is specific to CD30 on hematologicalmalignancies (Klussman et al., Bioconjugate Chemistry 15(4):765-773(2004); Doronina et al. Nature Biotech. 21(7):778-784 (2003); Franciscoet al. Blood 102(4):1458-1465 (2003); U.S. Patent Publication No.2004/0018194; (iii) anti-CD20 antibodies such as Rituxan® (rituximab)(WO 04/032828) for the treatment of CD20-expressing cancers and immunedisorders; (iv) anti-EphB2 antibodies 2H9 and anti-IL-8 for treatment ofcolorectal cancer (Mao et al. Cancer Res. 64(3):781-788 (2004)); (v)E-selectin antibody (Bhaskar et al. Cancer Res. 63:6387-6394 (2003));and (vi) other anti-CD30 antibodies (WO 03/043583). Monomethylauristatin(MMAE) has also been conjugated to 2H9, an antibody against EphB2R whichis a type 1 TM tyrosine kinase receptor with close homology betweenmouse and human, and is over-expressed in colorectal cancer cells (Maoet al., Cancer Res. 64:781-788 (2004)).

Monomethylauristatin MMAF, a variant of auristatin E (MMAE) with aphenylalanine at the C-terminus (U.S. Pat. Nos. 5,767,237 and6,124,431), has been reported to be less potent than MMAE, but morepotent when conjugated to monoclonal antibodies (Senter et al,Proceedings of the American Association for Cancer Research, Volume 45,Abstract Number 623, presented Mar. 28, 2004). Auristatin F phenylenediamine (AFP); a phenylalanine variant of MMAE was linked to ananti-CD70 mAb, 1F6, through the C-terminus of 1F6 via a phenylenediamine spacer (Law et al, Proceedings of the American Association forCancer Research, Volume 45, Abstract Number 625, presented Mar. 28,2004).

There exists a need in the art for additional drugs to treat diseasesand disorders associated angiogenesis including, e.g., aberrantangiogenesis associated with cancers dependent on the growth andproliferation of vasculature of endothelial origin. There also exists aneed in the art for additional endothelial cell-targeted anti-Robo4antibody-drug conjugates for the detection and visualization of bloodvessel growth and proliferation in, for example, cancers or oculardisorders supported or caused by excess proliferation of blood vessels,as well as in disorders or other physiological states in whichmonitoring blood vessel growth is useful in understanding or treatingthe physiological state. The present invention meets these and otherneeds.

SUMMARY OF THE INVENTION

The invention provides antibodies that specifically bind to Robo4(including, e.g., primate and/or rodent Robo4, such as human and/ormouse Robo4) and diagnostic and therapeutic methods using suchantibodies. In some embodiments, the antibodies are humanized or human.In some embodiments, the antibody is selected from the group consistingof: an intact antibody, an antibody variant, and antibody derivative, aFab, a Fab′, a (Fab′)₂, and an Fv. In one embodiment, the inventionprovides an anti-Robo4 antibody having affinity and specificity forhuman Robo4 and, optionally, murine Robo4, the antibody comprising,consisting of or consisting essentially of hypervariable regions (HVRs)of a light chain and heavy chain variable domain sequence as depicted inFIGS. 1A, 1B, 2A, and 2B (SEQ ID NOS:1-8, 17-71). In another embodiment,the invention provides an anti-Robo4 antibody having affinity andspecificity for human Robo4 and, optionally, murine Robo4, the antibodycomprising, consisting of or consisting essentially of framework regions(FRs) of a light chain and heavy chain variable domain sequence asdepicted in FIGS. 1A, 1B, 2A, 2B, 3A, 3B, 4A, and 4B (SEQ ID NOS:9-16,SEQ ID NO:12, where V is replaced by M, and SEQ ID NOS:99-139). Inanother embodiment, the invention provides an anti-Robo4 antibody havingaffinity and specificity for human Robo4 and, optionally, murine Robo4,the antibody comprising, consisting of or consisting essentially of thelight chain and heavy chain variable domain sequences as depicted inFIGS. 1A and 1B (SEQ ID NOS:72-97) and FIGS. 2A and 2B (SEQ ID NOS:140-165).

In one embodiment the invention provides an anti-Robo4 antibodycomprising: at least one, two, three, four, five, or six hypervariableregion (HVR) sequence(s) selected from the group consisting of:

(i) HVR-L1 comprising sequence A1-A11, wherein A1-A11 is RASQDVSTAVA(SEQ ID NO:1)

(ii) HVR-L2 comprising sequence B1-B7, wherein B1-B7 is SASFLYS (SEQ IDNO:2)

(iii) HVR-L3 comprising sequence C1-C9, wherein C1-C9 is QQSYTTPPT (SEQID NO:3)

(iv) HVR-H1 comprising sequence D1-D10, wherein D1-D10 is GFTINGYYIH(SEQ ID NO:17)

(v) HVR-H2 comprising sequence E1-E18, wherein E1-E18 isGFIYPAGGDTDYADSVKG (SEQ ID NO:18);

(vi) HVR-H3 comprising sequence F1-F17 wherein F1-F17 isARLIGNKFGWSSYGMDY (SEQ ID NO:19); and

(vii) at least one variant HVR, wherein the variant HVR comprises aninsertion, deletion, or substitution of at least one amino acid residueof the sequence depicted in SEQ ID NO: 1, 2, 3, 17, 18, or 19.

In another embodiment, the invention provides an anti-Robo4 antibodycomprising:

at least one, two, three, four, five or six hypervariable region (HVR)sequences selected from the group consisting of:

(i) HVR-L1 comprising sequence A1-A11, wherein A1-A11 is RASQDVSTAVA(SEQ ID NO:1)

(ii) HVR-L2 comprising sequence B1-B7, wherein B1-B7 is SASFLYS (SEQ IDNO:2)

(iii) HVR-L3 comprising sequence C1-C9, wherein C1-C9 is QQSYTTPPT (SEQID NO:3)

(iv) HVR-H1 comprising sequence D1-D10, wherein D1-D10 is GFTISGSWIH(SEQ ID NO:4)

(v) HVR-H2 comprising sequence E1-E18, wherein E1-E18 isAVITPAGGYTYYADSVKG (SEQ ID NO:5) and

(vi) HVR-H3 comprising sequence F1-F16, wherein F1-F16 isSNRYSGQFVPAYAMDY (SEQ ID NO:6).

In one embodiment, HVR-L1 of an antibody of the invention comprises thesequence of SEQ ID NO:1. In one embodiment, HVR-L2 of an antibody of theinvention comprises the sequence of SEQ ID NO:2. In one embodiment,HVR-L3 of an antibody of the invention comprises the sequence of SEQ IDNO:3. In one embodiment, HVR-H1 of an antibody of the inventioncomprises the sequence of SEQ ID NO:4. In one embodiment, HVR-H2 of anantibody of the invention comprises the sequence of SEQ ID NO:5. In oneembodiment, HVR-H3 of an antibody of the invention comprises thesequence of SEQ ID NO:6. In one embodiment, HVR-L1 comprises RASQSISSYLA(SEQ ID NO:7) or RASQDGARSLA (SEQ ID NO:39) or RASQDGAIYLA (SEQ IDNO:40). In one embodiment, HVR-L2 comprises GASSRAS (SEQ ID NO:8) orSASFLAS (SEQ ID NO:41) or SASLES (SEQ ID NO:42) or SATLAS (SEQ ID NO:43)or SASFLAS (SEQ ID NO:44) or SASNLAS (SEQ ID NO:45) or SASTLAS (SEQ IDNO:46). In one embodiment, an antibody of the invention comprising thesesequences (in combination as described herein) is humanized or human.

In one aspect, the invention provides an antibody comprising one, two,three, four, five or six HVRs, wherein each HVR comprises, consists orconsists essentially of a sequence selected from the group consisting ofSEQ ID NOS: 1, 2, 3, 4, 5, 6, 7, and 8, and wherein SEQ ID NO: 1 or 7corresponds to an HVR-L1, SEQ ID NO:2 or 8 corresponds to an HVR-L2, SEQID NO:3 corresponds to an HVR-L3, SEQ ID NO:4 corresponds to an HVR-H1,SEQ ID NO:5 corresponds to an HVR-H2, and SEQ ID NO:6 corresponds to anHVR-H3. In one embodiment, an antibody of the invention comprises anHVR-L1 comprising SEQ ID NO:7, an HVR-L2 comprising SEQ ID NO:2, anHVR-L3 comprising SEQ ID NO:3, an HVR-H1 comprising SEQ ID NO:4, anHVR-H2 comprising SEQ ID NO:5, and an HVR-H3 comprising SEQ ID NO:6. Inanother embodiment, an antibody of the invention comprises an HVR-L1comprising SEQ ID NO:1, an HVR-L2 comprising SEQ ID NO:8, an HVR-L3comprising SEQ ID NO:3, an HVR-H1 comprising SEQ ID NO:4, an HVR-H2comprising SEQ ID NO:5, and an HVR-H3 comprising SEQ ID NO:6. In oneembodiment, an antibody of the invention comprises an HVR-L1 comprisingSEQ ID NO:1, an HVR-L2 comprising SEQ ID NO:2, an HVR-L3 comprising SEQID NO:3, an HVR-H1 comprising SEQ ID NO:4, an HVR-H2 comprising SEQ IDNO:5, and an HVR-H3 comprising SEQ ID NO:6. In another embodiment, anantibody of the invention comprises an HVR-L1 comprising SEQ ID NO:1, anHVR-L2 comprising SEQ ID NO:2, an HVR-L3 comprising SEQ ID NO:20, anHVR-H1 comprising SEQ ID NO:17, an HVR-H2 comprising SEQ ID NO:18, andan HVR-H3 comprising SEQ ID NO:19.

Variant HVRs in an antibody of the invention can have modifications ofone or more residues within the HVR. In one embodiment, a HVR-L1 variantcomprises SEQ ID NO:1 wherein A1-11 comprises 1-6 (1, 2, 3, 4, 5, or 6)substitutions in any combination of the following positions: A5 (S), A6(I or G), A7 (A), A8 (S, R, or I), A9 (Y or S), and A10 (L). In oneembodiment, a HVR-L2 variant comprises SEQ ID NO:2 wherein B1-7comprises 1-4 (1, 2, 3, 4, 5, or 6) substitutions in any combination ofthe following positions: B1 (G), B3 (T), B4 (S, L, N, or T), B5 (R, E,or A), B6 (A or S) and B7 (Y). In one embodiment, a HVR-L3 variantcomprises SEQ ID NO:3 wherein C1-9 comprises 1-6 (1, 2, 3, 4, 5, or 6)substitutions in any combination of the following positions: C3 (Y, P,T, F or G), C4 (W, F, R or N), C5 (S, N, A, D, F, H, V or G), C6 (Y, S,A, D, N, L, I, M, Y or G), C7 (L, H, or T) and C8 (L, F, A, M or S). Inone embodiment, a HVR-H1 variant comprises SEQ ID NO:4 wherein D1-10comprises 1-9 (1, 2, 3, 4, 5, 6, 7, 8 or 9) substitutions in anycombination of the following positions: D2 (Y), D3 (S), D4 (F or L), D5(N, T, Y, D, or K), D6 (N or S), D7 (Y, N or R), D8 (Y or A), D9 (M, F,L or N) and D10 (S, E or Q). In one embodiment, a HVR-H2 variantcomprises SEQ ID NO:5 wherein E1-18 comprises 1-10 (1, 2, 3, 4, 5, 6, 7,8, 9, or 10) substitutions in any combination of the followingpositions: E1 (G or S), E2 (F, G, I, T, or R), E4 (Y or S), E5 (G or S),E6 (T, Y, or M), E7 (D or L), E8 (S), E9 (D, S, T, H, K, A or V), E10(I), and E11 (D, N, A, E, or 1). In one embodiment, a HVR-H3 variantcomprises SEQ ID NO:6 wherein F1-18 comprises 1-17 (1, 2, 3, 4, 5, 6, 7,8, 9, 10, 11, 12, 13, 14, 15, 16 or 17) substitutions in any combinationof the following positions: F2 (S), F3 (L, G, D, M or W), F4 (I, G, V,or S), F5 (G, Y, or N), F6 (N, S, or V), F7 (K, Y, W, or M), F8 (F, S,P, or a deletion), F9 (G, A, S, Y, or a deletion), F10 (W, R, P, E, G,or a deletion), F11 (S, W, G, H, or a deletion), F12 (S, W, H, or adeletion), F13 (Y, D, G, V, or a deletion), F14 (G or a deletion), F15(V or a deletion), F16 (L or F), F17 (a), and F18 (V). Letter(s) inparenthesis following each position indicates an illustrativesubstitution (i.e., replacement) amino acid or, where indicated, anamino acid deletion. In one embodiment, a HVR-L1 comprises the sequenceof SEQ ID NO:1; a HVR-L2 comprises SEQ ID NO:2; a HVR-L3 variantcomprises SEQ ID NO:3 wherein C4, C5, C6, and C6 are R, S, D, and H,respectively; a HVR-H1 comprises SEQ ID NO:17; a HVR-H2 comprises SEQ IDNO:18; and a HVR-H3 comprises SEQ ID NO:19 or a HVR-H3 variantcomprising SEQ ID NO:19. In one embodiment of these antibodies, theseantibodies further comprise a human κI light chain framework consensussequence. In one embodiment, position 104 in framework region 4 of thelight chain (LC-FR4) (Kabat numbering) is V. In one embodiment, position104 of LC-FR4 is M.

In one embodiment, an antibody of the invention comprises a variantHVR-H1 SEQ ID NO:4 numbered D1-D10, wherein from 1 to 6 substitutionsare selected from the following: D2 (Y), D3 (S), D4 (F or L), D5 (S, T,Y, D, or K), D6 (N or S), D7 (S, N, or R), D8 (W or A), D9 (M, F, L orN), and D10 (S, E, or Q). In one embodiment, an antibody of theinvention comprises a variant HVR-H1 comprising SEQ ID NO:24, 25, 26, 27or 28. In one embodiment, an antibody of the invention comprises avariant HVR-H2 SEQ ID NO:5 numbered E1-E18, wherein from 1 to 7substitutions are selected from the following: E1 (A or S), E2 (V, G, I,T or R), E4 (T or S), E5 (G or S), E6 (T, Y, or M), E7 (D or L), E8 (S),E9 (Y, S, T, H, K, A or V), E10 (I) and E11 (Y, N, A, E, or 1). In oneembodiment, an antibody of the invention comprises a variant HVR-H2comprising SEQ ID NO:29, 30, 31, 32, or 33. In one embodiment, anantibody of the invention comprises a variant HVR-H3 comprising SEQ IDNO:6 numbered F1-F16, wherein from 1-15 substitutions are selected fromthe following: F1 (S, G, D, M, or W), F2 (N, G, V, or S), F3 (R, Y orN), F4 (Y, S, or V), F5 (S, Y, W or M), F6 (G, S, P or a deletion), F7(Q, A, S, Y, or a deletion), F8 (F, R, P, E, G, or a deletion), F9 (V,W, G, H, or a deletion), F10 (P, W, H, or a deletion), F11 (A, D, G, V,or a deletion), F12 (Y or a deletion), F13 (A or V), F14 (L or F), andF15 (V). According to the invention, an amino acid substitution mayencompass an amino acid deletion in a given sequence. In one embodimentof the invention, an antibody of the invention comprises a variantHVR-H3 comprising SEQ ID NO:34, 35, 36, 37, or 38. In one embodiment ofthese antibodies, the framework consensus sequence comprisessubstitution at position 71, 73 and/or 78. In some embodiments of theseantibodies, position 71 is A, 73 is T and/or 78 is A. In one embodimentof these antibodies, these antibodies further comprise a human subgroupIII heavy chain framework consensus sequence.

In one aspect, the invention provides an anti-Robo4 antibody comprisingone, two, three, four, five six, or more of the HVR sequences depictedin FIGS. 1, 2, 3, and (SEQ ID NOS:1-8, 17-71).

In one embodiment, the invention provides a humanized anti-Robo4antibody. A humanized anti-Robo4 antibody of the invention may compriseone or more human and/or human consensus non-hypervariable region (e.g.,framework) sequences in its heavy and/or light chain variable domain. Insome embodiments, one or more additional modifications are presentwithin the human and/or human consensus non-hypervariable regionsequences. In one embodiment, the heavy chain variable domain of anantibody of the invention comprises a human consensus frameworksequence, which in one embodiment is the subgroup III consensusframework sequence. In one embodiment, an antibody of the inventioncomprises a variant subgroup III consensus framework sequence modifiedat least one amino acid position. For example, in one embodiment, avariant subgroup III consensus framework sequence may comprise asubstitution at one or more of positions 71, 73 and/or 78. In oneembodiment, said substitution is R71A, N73T and/or N78A and/or L/78A, inany combination thereof. In one embodiment, the light chain variabledomain of an antibody of the invention comprises a human consensusframework sequence, which in one embodiment is the subgroup κI consensusframework sequence. In one embodiment, the light chain consensusframework sequence is modified at one or more positions. In oneembodiment, the light chain consensus sequence has at position 104 theamino acid V. In one embodiment, the light chain consensus sequence ismodified at position 104 according to the Kabat numbering system,wherein position 104 is M.

In one aspect, the invention provides an antibody comprising 1 to 4 orall of the light chain FR sequences LC-FR1 (SEQ ID NO:9), LC-FR2 (SEQ IDNO: 10, LC-FR3 (SEQ ID NO:11), and LC-FR4 (SEQ ID NO:12). In oneembodiment, LC-FR4 (SEQ ID NO:12) is a variant wherein position 104 isM.

In one aspect, the invention provides an antibody comprising 1 to 4 orall of the heavy chain FR sequences HC-FR1 (SEQ ID NO:13), HC-FR2 (SEQID NO:14), HC-FR3 (SEQ ID NO:15), and HC-FR4 (SEQ ID NO:16).

In one embodiment, the invention provides a therapeutic agent for use ina host subject that elicits little to no immunogenic response againstthe agent in said subject. For example, in one embodiment, the inventionprovides a humanized antibody that elicits and/or is expected to elicita human anti-mouse antibody response (HAMA) at a substantially reducedlevel in a host subject compared to a murine antibody raised againsthuman Robo4. In another example, the invention provides a humanizedantibody that elicits and/or is expected to elicit minimal or no humananti-mouse antibody response (HAMA). In one example, an antibody of theinvention elicits an anti-mouse antibody response that is at or below aclinically-acceptable level.

The invention also provides antibodies comprising modifications inhybrid hypervariable positions as described herein below. In oneembodiment, an antibody of the invention comprises a variant humansubgroup consensus framework sequence modified at one or more hybridhypervariable positions. In one embodiment, an antibody of the inventioncomprises a heavy chain variable domain comprising a variant humansubgroup III consensus framework sequence modified at one or more ofpositions 26-35, 49-65, 95-102, and 94. In one embodiment, an antibodyof the invention comprises a light chain variable domain comprising avariant human kappa subgroup I consensus framework sequence modified atone or more of positions 24-34, 50-56, and 39-97.

In one embodiment, an antibody of the invention comprises at least aportion (or all) of the framework sequence of human κ light chain. Inone embodiment, an antibody of the invention comprises at least aportion (or all) of human κ subgroup I framework consensus sequence. Inone embodiment, an antibody of the invention comprises the frameworksequences shown in FIGS. 3A and 3B.

An antibody of the invention can comprise any suitable human or humanconsensus heavy chain framework sequences, provided the antibodyexhibits the desired biological characteristics (e.g., a desired bindingaffinity). In one embodiment, an antibody of the invention comprises atleast a portion (or all) of the framework sequence of human subgroup IIIheavy chain. In one embodiment, an antibody of the invention comprisesthe framework sequences shown in FIGS. 4A and 4B.

In one embodiment, an antibody of the invention comprises a heavy and/orlight chain variable domain comprising framework sequence depicted inSEQ ID NOS:72-137 (FIGS. 1A, 1B, 2A, 2B, 3A, 3B, 4A and 4B).

In one aspect, an antibody of the invention is a humanized anti-Robo4antibody that binds human Robo4 vascular endothelial cell marker. Forexample, in one embodiment, an antibody of the invention binds humanRobo4 with an IC50 value that is, less than 1000 nM, less than 500 nM,less than 200 nM, less than 100 nM, less than 50 nM, less than 30 nM,less than 20 nM less than 10 nM, less than 5 nM, less than 3 nM, lessthan 1 nM, less than 0.1 nM, or less than 0.01 nM. Comparison ofabilities to inhibit ligand binding to its receptor can be performedaccording to various methods known in the art, including as described inthe Examples below.

In one aspect, an antibody of the invention is an anti-Robo4 antibodyconjugated to a cytotoxic moiety (an anti-Robo4 antibody drug conjugate,also referred to as an anti-Robo4 ADC), wherein the anti-Robo4ADCinhibits Robo4-dependent cell proliferation in a cell expressing Robo4.Robo4 expressing cells include, but are not limited to, endothelialcells such as vascular endothelial cells. Exemplary anti-Robo4 ADCs aredisclosed herein. In one embodiment, the anti-Robo4 antibody ishumanized. In one embodiment, the anti-Robo4 antibody is a humanantibody. In one embodiment, the anti-Robo4 antibody is derived fromphage display mutagenesis and selection.

In one aspect, an antibody of the invention is an anti-Robo4 antibodyADC that inhibits Robo4-dependent cell proliferation better than areference anti-Robo4 antibody that is not conjugated to a cytotoxicagent. For example, in one embodiment, an anti-Robo4 ADC antibody of theinvention inhibits cell proliferation with an IC50 value that is lessthan about half that of the reference anti-Robo4 antibody that is notconjugated to a cytotoxic agent. In one embodiment, the IC50 value of anADC antibody of the invention is about 0.001, 0.01 0.1, 0.2, 0.3 or 0.4that of the non-ADC reference antibody. Comparison of abilities toinhibit cell proliferation can be performed according to various methodsknown in the art, including as described in the Examples below. In oneembodiment, IC50 values are determined across an antibody concentrationrange from about 0.01 nM to about 100 nM.

In one embodiment, both the humanized antibody and chimeric antibody aremonovalent. In one embodiment, both the humanized antibody and chimericantibody comprise a single Fab region linked to an Fc region. In oneembodiment, the reference chimeric antibody comprises variable domainsequences depicted in FIG. 7 (SEQ ID NO: 9 and 10) linked to a human Fcregion. In one embodiment, the human Fc region is that of an IgG (e.g.,IgG1, 2, 3 or 4).

In one aspect, the antibody of the invention comprises an Fc region. Inan embodiment, the Fc region is an IgG1, 2, 3 or 4. In one embodimentthe IgG is a native IgG. In one embodiment, the Fc region exhibitsenhance antibody dependent cellular cytotoxicity (ADCC) relative to wildtype ADCC activity of the native IgG1, 2, 3, or 4. In one embodiment,the IgG is an Fc region altered from the native IgG such that thealtered Fc region exhibits enhanced ADCC activity relative to the nativeFc region.

In one aspect, an antibody of the invention is an anti-Robo4 antibodyconjugated to a detectable moiety, such as an imaging agent. In oneaspect, antibodies of the invention may be conjugated with any labelmoiety which can be covalently attached to the antibody through areactive moiety, an activated moiety, or a reactive cysteine thiol group(Singh et al., Anal. Biochem. 304:147-15 (2002); Harlow E. and Lane, D.(1999) Using Antibodies: A Laboratory Manual, Cold Springs HarborLaboratory Press, Cold Spring Harbor, N.Y.; Lundblad R. L. (1991)Chemical Reagents for Protein Modification, 2nd ed. CRC Press, BocaRaton, Fla.). The attached label may function to: (i) provide adetectable signal; (ii) interact with a second label to modify thedetectable signal provided by the first or second label, e.g. to giveFRET (fluorescence resonance energy transfer); (iii) stabilizeinteractions or increase affinity of binding, with antigen or ligand;(iv) affect mobility, e.g. electrophoretic mobility orcell-permeability, by charge, hydrophobicity, shape, or other physicalparameters, or (v) provide a capture moiety, to modulate ligandaffinity, antibody/antigen binding, or ionic complexation. Labeledantibodies of the invention are further disclosed herein.

In an embodiment, the detectable label is an aqueous insoluble particlethat is detectable in vitro or in vivo. In an embodiment, the particleis a magnetic or metallic particle. Metallic particles are detectable bysuch methods as magnetic resonance imaging (MRI), single-particle orsingle-molecule tracking, immunocytochemistry, plasmon frequency withdark-field illumination, differential interference contrast and videoenhancement, total internal reflection, and photothermal interferencecontrast (PIC) technique (see, for example PNAS USA 100(20): 11350-11355(2003); Sheetz et al., Nature 340:284-288 (1989); Baschong et al.,Histochemistry 83:409-411 (1985); Slot and Geuze, Eur. J. Cell Biol.38:87-93 (1935); Frey and Frey, J. Struct. Biol. 127:94-100 (1999);Hainfeld and Powell, J. Histochem. Cytochem. 48:471-480 (2000); Schultzet al., PNAS USA 97:996-1001 (2000); Gelles et al., Nature 331:450-453(1988); Sonnichsen et al., Appl. Phys. Lett. 77:2949-2951 (2000); Boyeret al., Science 297:1160-1163 (2002)). Nanoparticulate agents of theinvention may also include, but are not limited to, microbubbles (seeEllegala et al., Circulation 108:336-341 (2003)), also referred to asacoustically active lipospheres (AALs) (see Tartis et al., UltrasoundMed. Biol. 32(11): 1771-80 (2006)), superparamagnetic agents, liposomes,perfluorocarbon nanoparticle emulsions (WO 2005104051), and dendrimers(see Caruthers et al., Methods in Molecular Medicine, 124:387-400 (2006)and references cited therein, all of which references are herebyincorporated by reference in their entirety).

In one aspect, the invention provides an antibody comprising a heavychain variable domain comprising the HVR-H1, HVR-H2 and/or HVR-H3sequence depicted in FIGS. 1B and 2B. In one embodiment, the variabledomain comprises HC-FR1, HC-FR2, HC-FR3 and/or HC-FR4 sequence depictedin FIGS. 1B, 2B, 4A and 4B. In one embodiment, the antibody comprises aCH1 and/or Fc sequence. In one embodiment, an antibody of the inventioncomprises a heavy chain variable domain comprising the HVR-H1, HVR-H2and/or HVR-H3 sequence, and the HC-FR1, HC-FR2, HC-FR3 and/or HC-FR4sequence depicted in FIGS. 1B, 2B, 4A, and 4B. In one embodiment, anantibody of the invention comprises a heavy chain variable domaincomprising the HVR1-HC, HVR2-HC and/or HVR3-HC sequence depicted inFIGS. 1B, 2B, 4A and 4B, and a CH1 and/or Fc sequence.

In one aspect, the invention provides an antibody comprising a lightchain variable domain comprising HVR1-LC, HVR2-LC and/or HVR3-LCsequence depicted in FIG. 1A or 2A. In one embodiment, the variabledomain comprises a FR1-LC, FR2-LC, FR3-LC and/or FR4-LC sequencedepicted in FIGS. 3A and 3B.

In one embodiment, an antibody of the invention comprises light andheavy chain variable domains as described in the preceding twoparagraphs. In one embodiment, the antibody is monovalent and comprisesan Fc region. In one embodiment, the Fc region comprises at least oneprotuberance (knob) and at least one cavity (hole), wherein presence ofthe protuberance and cavity enhances formation of a complex between anFc polypeptide comprising the protuberance and an Fc polypeptidecomprising the cavity, for example as described in WO 2005/063816. Inone embodiment, the Fc region of an antibody of the invention comprisesa first and a second Fc polypeptide, wherein the first and secondpolypeptide each comprises one or more mutations with respect to wildtype human Fc. In one embodiment, a cavity mutation is T366S, L368Aand/or Y407V. In one embodiment, a protuberance mutation is T366W. Inone embodiment, the first polypeptide comprises the Fc sequence depictedin FIG. 13 and the second polypeptide comprises the Fc sequence depictedin FIG. 14.

In one embodiment, the invention provides methods of modulating one ormore aspects of Robo4-associated effects (e.g., Robo4 activation,downstream molecular signaling (e.g., mitogen activated protein kinase(MAPK) phosphorylation), cell proliferation, cell migration, cellsurvival, cell morphogenesis and angiogenesis) by administering ananti-Robo4 antibody to a subject (e.g., a mammalian subject such as ahuman). In some embodiments, the anti-Robo4 antibody disrupts ligandbinding to Robo4 (e.g., by binding to a sequence within the Robo4extracellular domain, and thereby inhibiting interaction of said bounddomain with its binding partner (such as a ligand molecule). In otherembodiments, the Robo4 antibody binds to a sequence that is not withinthe Robo4 ligand binding site, wherein said binding results indisruption of the ability of the Robo4 to interact with its bindingpartner.

In one embodiment of the invention, binding of the antibody to Robo4inhibits Robo4 associated endothelial cell proliferation. In anotherembodiment of a Robo4 antibody of the invention, binding of the antibodyto Robo4 in a cell inhibits proliferation, survival, scattering,morphogenesis and/or motility of the cell. In another embodiment, thecell is an endothelial cell, such as, without limitation, a vascularendothelial cell.

In one embodiment, a Robo4 antibody of the invention specifically bindsat least a portion of Robo4 shown in FIG. 5 (SEQ ID NO:138) or variantthereof. In one embodiment, an antibody of the invention specificallybinds within the full length Robo4 amino acid sequence lacking theleader sequence (i.e., lacking the region indicated by dottedunderlining in FIG. 5). In one embodiment, an antibody of the inventionspecifically binds within the extracellular domain sequence shown inFIG. 5 (indicated by solid underlining in FIG. 5). In one embodiment, anantibody of the invention specifically binds a conformational epitopeformed by part or all of the Robo4 extracellular domain. In oneembodiment, an antibody of the invention specifically binds an aminoacid sequence having at least 50%, 60%, 70%, 80%, 90%, 95%, 98% sequenceidentity or similarity with the sequence shown in FIG. 5 (SEQ IDNO:138). In one embodiment, an antibody of the invention specificallybinds an amino acid sequence having at least 50%, 60%, 70%, 80%, 90%,95%, 98% sequence identity or similarity with the sequence of the Robo4full length amino acid sequence lacking the leader sequence (i.e.,lacking the region indicated by dotted underlining in FIG. 5). In oneembodiment, an antibody of the invention specifically binds an aminoacid sequence having at least 50%, 60%, 70%, 80%, 90%, 95%, 98% sequenceidentity or similarity with the sequence of the Robo4 extracellulardomain (the region indicated by solid underlining in FIG. 5).

In one embodiment, an antibody of the invention specifically binds toRobo4 of a first animal species, and does not specifically bind to Robo4of a second animal species. In one embodiment, the first animal speciesis human and/or primate (e.g., cynomolgus monkey), and the second animalspecies is ratus (e.g., rat), murine (e.g., mouse) and/or canine. In oneembodiment, the first animal species is human. In one embodiment, thefirst animal species is primate, for example cynomolgus monkey. In oneembodiment, the second animal species is murine, for example mouse. Inone embodiment, the second animal species is canine. In one embodiment,an antibody of the invention specifically binds to Robo4 of at least twospecies. In one embodiment, the first animal species is human and/orprimate (e.g., cynomolgus monkey), and the second animal species ismurine (e.g., mouse). Antibodies of the invention that bind more thanone species find use in animal modeling studies for therapeutic ordiagnostic agents.

In one aspect, the invention provides a method of detecting Robo4 inserum of a mammal, where a concentration of Robo4 in the serum that ishigher than normal levels of Robo4 indicate the presence of angiogenesisin the mammal. According to the method of the invention, a detectable ordetectably labeled anti-Robo4 antibody of the invention is contactedwith a serum sample from a test mammal, including but not limited to ahuman. The anti-Robo4 antibody is detected directly via the detectablelabel or indirectly by, for example, contact with a detectably labeledor detectable secondary antibody. A serum concentration (level) ofanti-Robo4 in the test mammal that is higher than anti-Robo4 serumconcentration from a normal mammal indicates angiogenesis in the testmammal. A normal mammal refers to a mammal known not to be experiencingangiogenesis or a population of mammals not experiencing angiogenesis.In one embodiment the test and normal mammal or population of mammals isthe same species, including but not limited to humans. Serum levels ofRobo4 protein have been detected in human patients with advancednon-small cell lung cancer (Gom et al., Lung Cancer 49:71-76 (2005)).Serum anti-Robo4 levels are useful for diagnosis and prognosis ofangiogenesis associated with cancer.

In one aspect, the invention provides compositions comprising one ormore antibodies of the invention and a carrier. In one embodiment, thecarrier is pharmaceutically acceptable.

In one aspect, the invention provides nucleic acids encoding a Robo4antibody of the invention, vectors comprising the nucleic acids, andhost cells (e.g., E. coli or Chinese Hamster Ovary (CHO) cells),comprising the nucleic acids and/or vectors.cells comprising a nucleicacid or a vector of the invention. A vector can be of any type, forexample a recombinant vector such as an expression vector. Any of avariety of host cells can be used. In one embodiment, a host cell is aprokaryotic cell, for example, E. coli. In one embodiment, a host cellis a eukaryotic cell, for example a mammalian cell such as ChineseHamster Ovary (CHO) cell.

In one aspect, the invention provides methods for making an anti-Robo4.For example, the invention provides a method of making a Robo4 antibody,the method comprising expressing in a suitable host cell a recombinantvector of the invention encoding said antibody (or fragment thereof),and recovering said antibody.

In one aspect, the invention provides an article of manufacturecomprising a container; and a composition contained within thecontainer, wherein the composition comprises one or more anti-Robo4antibodies of the invention. In one embodiment, the compositioncomprises a nucleic acid of the invention. In one embodiment, acomposition comprising an antibody further comprises a carrier, which insome embodiments is pharmaceutically acceptable. In one embodiment, anarticle of manufacture of the invention further comprises instructionsfor administering the composition (e.g., the antibody) to a subject.

In one aspect, the invention provides a kit comprising a first containercomprising a composition comprising one or more anti-Robo4 antibodies ofthe invention; and a second container comprising a buffer. In oneembodiment, the buffer is pharmaceutically acceptable. In oneembodiment, a composition comprising an antibody further comprises acarrier, which in some embodiments is pharmaceutically acceptable. Inone embodiment, a kit further comprises instructions for administeringthe composition (e.g., the antibody) to a subject.

In one aspect, the invention provides use of a Robo4 antibody of theinvention in the preparation of a medicament for the therapeutic and/orprophylactic treatment of a disease, such as a cancer, a tumor, a cellproliferative disorder, an immune (such as autoimmune) disorder and/oran angiogenesis-related disorder.

In one aspect, the invention provides use of a nucleic acid of theinvention in the preparation of a medicament for the therapeutic and/orprophylactic treatment of a disease, such as a cancer, a tumor, a cellproliferative disorder, an immune (such as autoimmune) disorder and/oran angiogenesis-related disorder.

In one aspect, the invention provides use of an expression vector of theinvention in the preparation of a medicament for the therapeutic and/orprophylactic treatment of a disease, such as a cancer, a tumor, a cellproliferative disorder, an immune (such as autoimmune) disorder and/oran angiogenesis-related disorder.

In one aspect, the invention provides use of a host cell of theinvention in the preparation of a medicament for the therapeutic and/orprophylactic treatment of a disease, such as a cancer, a tumor, a cellproliferative disorder, an immune disorder (e.g., an autoimmune disordersuch as, for example rheumatoid arthritis) and/or anangiogenesis-related disorder.

In one aspect, the invention provides use of an article of manufactureof the invention in the preparation of a medicament for the therapeuticand/or prophylactic treatment of a disease, such as a cancer, a tumor, acell proliferative disorder, an immune disorder (e.g., an autoimmunedisorder such as, for example rheumatoid arthritis) and/or anangiogenesis-related disorder.

In one aspect, the invention provides use of a kit of the invention inthe preparation of a medicament for the therapeutic and/or prophylactictreatment of a disease, such as a cancer, a tumor, a cell proliferativedisorder, an immune (such as autoimmune) disorder and/or anangiogenesis-related disorder.

The invention provides methods and compositions useful for modulatingdisease states associated with dysregulation of the Robo4 signalingaxis. The Robo4 signaling pathway is involved in multiple biological andphysiological functions, including, e.g., cell proliferation andangiogenesis. Thus, in one aspect, the invention provides a methodcomprising administering to a subject an antibody of the invention.

In one aspect, the invention provides a method of inhibiting Robo4activated cell proliferation, said method comprising contacting a cellor tissue with an effective amount of a antibody of the invention,whereby cell proliferation associated with Robo4 activation isinhibited.

In one aspect, the invention provides a method of treating apathological condition associated with dysregulation of Robo4 activationin a subject, said method comprising administering to the subject aneffective amount of an antibody of the invention, whereby said conditionis treated.

In one aspect, the invention provides a method of inhibiting the growthof a cell that expresses Robo4, said method comprising contacting saidcell with an antibody of the invention or an antibody drug conjugate ofthe invention, thereby causing an inhibition of growth of said cell.

In one aspect, the invention provides a method of therapeuticallytreating a mammal having a cancerous tumor comprising a cell thatexpresses Robo4, said method comprising administering to said mammal aneffective amount of an antibody of the invention or an antibody drugconjugate of the invention, thereby effectively treating said mammal.

In one aspect, the invention provides a method for treating orpreventing a cell proliferative disorder associated with increasedexpression or activity of Robo4, said method comprising administering toa subject in need of such treatment an effective amount of an antibodyof the invention or an antibody drug conjugate of the invention, therebyeffectively treating or preventing said cell proliferative disorder. Inone embodiment, said proliferative disorder is a pathological conditionassociated with abnormal or unwanted endothelial cell proliferation,such as abnormal or unwanted vascular cell proliferation in disordersincluding, but not limited to, cancer, angiogenesis and disordersassociated with (e.g., augmented by endothelial cell proliferationwithin the tissue experiencing the disorder) solid tumors andmetastasis, atherosclerosis, retrolental fibroplasia, hemangiomas,chronic inflammation, intraocular neovascular diseases such asproliferative retinopathies, e.g., diabetic retinopathy, age-relatedmacular degeneration (AMD), neovascular glaucoma, immune rejection oftransplanted corneal tissue and other tissues, rheumatoid arthritis, andpsoriasis.

In another aspect, the invention provides a method of therapeuticallytreating a tumor in a mammal, wherein the growth of said tumor is atleast in part dependent upon a growth potentiating effect of Robo4expressed in endothelial cells, including without limitation vascularendothelial cells, the method comprising contacting said cell with aneffective amount of an antibody of the invention or an antibody drugconjugate of the invention, thereby inhibiting the growth of endothelialcells in, for example, angiogenesis associated with the tumor, andthereby effectively treating said tumor.

Yet another embodiment of the invention provides methods of modulatingangiogenesis, by contacting a cell or tissue with an effective amount ofan anti-Robo4 antibody described herein. In some embodiments, theantibody further comprises a cytotoxic agent. In some embodiments, theangiogenesis is inhibited. In some embodiments, the angiogenesis isenhanced. In some embodiments, the angiogenesis is associated with adisorder selected from: cancer, atherosclerosis, retrolentalfibroplasia, hemangiomas, chronic inflammation, intraocular neovasculardiseases, proliferative retinopathies, diabetic retinopathy, age-relatedmacular degeneration (AMD), neovascular glaucoma, immune rejection oftransplanted corneal tissue and other tissues, rheumatoid arthritis,psoriasis, and combinations thereof. In some embodiments, theangiogenesis is associated with cancer. In some embodiments, the canceris selected from the group consisting of: sarcomas including osteogenicsarcomas and angiosarcomas, squamous cell cancer, lung cancer, cancer ofthe peritoneum, hepatocellular cancer, gastric or stomach cancerincluding gastrointestinal cancer, pancreatic cancer, glioblastoma,cervical cancer, ovarian cancer, liver cancer, bladder cancer, cancer ofthe urinary tract, hepatoma, breast cancer, colon cancer, rectal cancer,colorectal cancer, endometrial or uterine carcinoma, salivary glandcarcinoma, kidney or renal cancer, prostate cancer, vulval cancer,thyroid cancer, hepatic carcinoma, anal carcinoma, penile carcinoma,melanoma, multiple myeloma and B-cell lymphoma, brain cancer, head andneck cancer, and associated metastases and combinations thereof. In someembodiments, the cell or tissue is in a mammal. In some embodiments, themammal is a human. In some embodiments, the methods further comprisecontacting the cell with an agent selected from: an anti-neoplasticagent, chemotherapeutic agent, a growth inhibitory agent, a cytotoxicagent, an anti-angiogenic agent, and combinations thereof. In someembodiments, the agent is an anti-VEGF antibody. In some embodiments,the methods further comprise contacting the cell with a second, third,or fourth agent selected from: an anti-neoplastic agent,chemotherapeutic agent, a growth inhibitory agent, a cytotoxic agent, ananti-angiogenic agent, and combinations thereof. In some embodiments,the second, third, or fourth agent is an anti-VEGF antibody.

Methods of the invention can be used to affect any suitable pathologicalstate, for example, cells and/or tissues associated with upregulation ofthe Robo4 expression. In one embodiment, a cell that is targeted in amethod of the invention is an endothelial cell or vascular endothelialcell proliferating within a tumor (including, e.g., a breast cancer, acolorectal cancer, a lung cancer, a papillary carcinoma (e.g., of thethyroid gland), a colon cancer, a pancreatic cancer, an ovarian cancer,a cervical cancer, a central nervous system cancer, an osteogenicsarcoma, a renal carcinoma, a hepatocellular carcinoma, a bladdercancer, a gastric carcinoma, a head and neck squamous carcinoma, amelanoma and a leukemia, or, a sarcomas (e.g., an osteogenic sarcoma oran angiosarcoma), or any cancer the growth of which is supported byendothelial cell proliferation in angiogenesis). In one embodiment, thepathological conditions are associated with abnormal or unwantedendothelial cell proliferation. In some embodiments, the target of ananti-Robo4 antibody or antibody drug conjugate of the invention,includes abnormal or unwanted vascular cell proliferation in disordersincluding, but not limited to, cancer, (including, e.g., solid tumorsand metastasis), atherosclerosis, retrolental fibroplasia, hemangiomas,chronic inflammation, intraocular neovascular diseases such asproliferative retinopathies, e.g., diabetic retinopathy, age-relatedmacular degeneration (AMD), neovascular glaucoma, immune rejection oftransplanted corneal tissue and other tissues, rheumatoid arthritis,psoriasis, and disorders associated with angiogenesis (including, e.g.,disorders augmented by endothelial cell proliferation within the tissueexperiencing the disorder).

Methods of the invention can further comprise additional treatmentsteps. For example, in one embodiment, a method further comprises a stepwherein a targeted cell and/or tissue (e.g., a cancer cell) is exposedto radiation treatment or a chemotherapeutic agent.

In one embodiment of methods of the invention, a cell that is targeted(e.g., an endothelial cell of a tumor tissue or a retina) is one inwhich Robo4 expression is increased as compared to an endothelial cellin normal tissue of the same tissue origin. In one embodiment, a methodof the invention causes the death of a targeted cell. For example,contact with an anti-Robo4 antibody of the invention, including contactwith an antibody drug conjugate of the invention, results in uptake ofthe cytotoxic moiety, which causes cell death. Alternatively, contactwith an anti-Robo4 antibody of the invention conjugated to a cytotoxiccompound may result in internalization of the cytotoxic compound, whichresults in cell death. In another alternative embodiment, contact withan anti-Robo4 antibody of the invention conjugated to a detectablemoiety causes the endothelial cells of, for example, vasculature of atissue (e.g. a tumor tissue or retina) to be detected, such as byimaging techniques well known in the relevant art.

Another embodiment of the invention provides methods of in vivo imaging,by administering an anti-Robo4 antibody described herein to a mammal. Insome embodiments the mammal is a human. In some embodiments, the mammalis suspected of having a disease or disorder selected from: cancer,atherosclerosis, retrolental fibroplasia, hemangiomas, chronicinflammation, intraocular neovascular diseases, proliferativeretinopathies, diabetic retinopathy, age-related macular degeneration(AMD), neovascular glaucoma, immune rejection of transplanted cornealtissue, rheumatoid arthritis, psoriasis, and combinations thereof.

Another embodiment of the invention provides methods of detecting a cellexpressing Robo4, by contacting the cell with an anti-Robo4 antibodydescribed herein. In some embodiments, the cell is a vascularendothelial cell. In some embodiments, the cell is in a mammal. In someembodiments, the mammal is suspected of having a disease or disorderselected from: cancer, atherosclerosis, retrolental fibroplasia,hemangiomas, chronic inflammation, intraocular neovascular diseases,proliferative retinopathies, diabetic retinopathy, age-related maculardegeneration (AMD), neovascular glaucoma, immune rejection oftransplanted corneal tissue, rheumatoid arthritis, psoriasis, andcombinations thereof. In some embodiments, the mammal is suspected ofhaving a cancer selected from: squamous cell cancer, lung cancer, cancerof the peritoneum, hepatocellular cancer, gastric or stomach cancerincluding gastrointestinal cancer, pancreatic cancer, glioblastoma,cervical cancer, ovarian cancer, liver cancer, bladder cancer, cancer ofthe urinary tract, hepatoma, breast cancer, colon cancer, rectal cancer,colorectal cancer, endometrial or uterine carcinoma, salivary glandcarcinoma, kidney or renal cancer, prostate cancer, vulval cancer,thyroid cancer, hepatic carcinoma, anal carcinoma, penile carcinoma,melanoma, multiple myeloma and B-cell lymphoma, brain cancer, head andneck cancer, and associated metastases and combinations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B depict alignment of amino acid sequences of the variableregions of the light and heavy chains for various anti-Robo4 clones ofthe invention (FIGS. 1A and 1B, respectively). The hypervariable regions(HVRs) of the light and heavy chains are indicated under the boxedcomplementary determining regions (CDRs). In FIG. 1A, the light chainHVRs-L1, L2, and L3 are Kabat positions 24-34, 50-56, and 89-102,respectively. In FIG. 1B, the heavy chain HVRs-H1, H2, and H3 are Kabatpositions 26-35, 49-65, and 93-102, respectively. Clones were preparedby phage display as disclosed in the Examples and sequenced.

FIGS. 2A and 2B depict amino acid sequences of the variable regions ofthe light and heavy chains (FIGS. 2A and 2B, respectively) of selectedaffinity-matured antibodies from libraries with individually-randomizedHVR. The HVRs in FIGS. 2A and 2B are the same positions as depicted inFIGS. 1A and 1B.

FIGS. 3A, 3B, 4A and 4B depict exemplary acceptor human consensusframework sequences for use in practicing the instant invention withsequence identifiers as follows:

Variable light (VL) consensus framework regions minus Kabat HVRs (FIGS.3A and 3B) human VL kappa subgroup I consensus frameworks 1-4 (SEQ IDNOS:9, 10, 99, 100) human VL kappa subgroup I′ consensus frameworks 1-4(SEQ ID NOS:9, 101, 99, 100) human VL kappa subgroup II consensusframeworks 1-4 (SEQ ID NOS:102, 103, 104, 100) human VL kappa subgroupIII consensus frameworks 1-4 (SEQ ID NOS:105, 106, 107, 100) human VLkappa subgroup IV consensus frameworks 1-4 (SEQ ID NOS:108, 109, 110,100) The locations of Kabat HVRs L1, L2, and L3 within the frameworksequences are depicted as shaded boxes.

Variable heavy (VH) consensus framework regions minus Kabat HVRs (FIGS.4A and B) human VH subgroup I consensus frameworks 1-4 minus Kabat HVRs(Subgroup IA, SEQ ID NOS:111, 112, 113, 16) and (subgroup IB, SEQ IDNOS:114, 115, 113, 16) human VH subgroup I consensus framework 1-4 minusextended HVRs, (subgroup IC, SEQ ID NOS:114, 115, 116, 16) and (subgroupID, SEQ ID NOS:114, 115, 117, 16) human VH subgroup II consensusframework 1-4 minus Kabat HVRs (subgroup IIA, SEQ ID NOS:118, 119, 120,16), (subgroup IB, SEQ ID NOS:121, 122, 120, 16) human VH subgroup IIconsensus framework 1-4 minus extended HVRs (subgroup IIC, SEQ IDNOS:121, 122, 123, 16), (subgroup IID, SEQ ID NOS:121, 122, 124, 16)human VH subgroup III consensus frameworks 1-4 minus Kabat HVRs(subgroup IIIA, SEQ ID NO:125, 126, 127, 16), (subgroup IIIB, SEQ IDNOS:128, 129, 127, 16) human VH subgroup III consensus frameworks 1-4minus extended HVRs (subgroup IIIC, SEQ ID NOS:128, 129, 130, 16),(subgroup IIID, SEQ ID NOS:128, 129, 131, 16) human VH acceptor 1frameworks 1-4 minus Kabat HVRs (subgroup Acceptor 1A, SEQ ID NOS:132,126, 133, 16) and (subgroup Acceptor 1B, SEQ ID NOS:128, 129, 133, 16)human VH acceptor 1 frameworks 1-4 minus extended HVRs (subgroupAcceptor 1C, SEQ ID NOS:128, 129, 134, 16) human VH acceptor 2frameworks 1-4 minus Kabat HVRs (subgroup Acceptor 2A, SEQ ID NOS:132,126, 135, 16) and (subgroup Acceptor 2B, SEQ ID NOS:128, 129, 135, 16)human VH acceptor 2 frameworks 1-4 minus extended HVRs (subgroupAcceptor 2C, SEQ ID NOS:128, 129, 136, 16) and (subgroup Acceptor 2D,SEQ ID NOS:128, 129, 137, 16).

FIG. 5A depicts the full length amino acid sequence of the Robo4polypeptide. A potential signal sequence is indicated by dottedunderlining. A portion of the extracellular domain is indicated by solidunderlining. FIG. 5B depicts the sequence of the His-tagged solubleRobo4 extracellular domain fragment (SEQ ID NO:171) used in, forexample, anti-Robo4 Fab phage display experiments disclosed herein. TheRobo4 extracellular domain was linked to a histidine tag for ease ofrecovery or detection.

FIG. 6A depicts the full length sequence of anti-Robo4 antibody YW71.22heavy chain (SEQ ID NO:169). The alanine shown in bold text andunderlined is the position at which a cysteine was substituted togenerate the thioMAb. FIG. 6B depicts the full length sequence ofanti-Robo4 antibody YW71.22 light chain (SEQ ID NO:170).

FIG. 7 depicts the amino acid sequence of murine Robo4 extracellulardomain comprising a potential signal sequence and having the histidinetag RRA(H)₅ attached at position H232 (SEQ ID NO:172). A dottedunderline indicates the potential signal sequence which is cleavedduring expression in mammalian cells.

FIG. 8 is a bar graph of the results of a HUVEC migration assay usingRobo4 constructs.

FIG. 9 shows the results of a BiaCore assay indicating that Robo4 doesnot bind Slit2.

FIG. 10 shows the results of a BiaCore assay indicating that Robo4interacts with UNC5B.

FIG. 11 is a photograph of an ISH assay showing that Robo4 is expressedin fetal mouse endothelium.

FIGS. 12A and 12B show expression of Robo4 in human HM-7 colon cancermouse xenograft tumor model. FIGS. 12C and 12D show Robo4 expression inhuman MDA-MB-175 breast cancer tumor mouse xenograft model.

FIGS. 13A-D show expression of Robo4 in human malignant melanoma.

FIGS. 14A-D show expression of Robo4 in small cell lung cancer. FIGS.14E-H show Robo4 expression in colon cancer.

FIGS. 15A-15C depict internalization of anti-Robo4 antibody 71.22 bymouse MS1 cells (FIGS. 15A and 15B), and internalization of affinitymatured anti-Robo4 antibody 71.22.S1.16 by mouse MS1 cells (FIG. 15C).

FIG. 16 is a bar graph showing the results of endothelial cell migrationassay. Anti-Robo4 antibody did not block VEGF induced EC migration.

FIG. 17 is a graph of changes in median tumor volume as a function oftime in xenograft mouse models dosed with control, anti-VEGF, anti-Robo4(YW71.22), and anti-Robo4 plus anti-VEGF antibodies. Naked Robo4antibody did not inhibit tumor growth in these experiments.

FIGS. 18A and 18B show the results of FACS plots indicating thataffinity matured anti-Robo4 clones 71.22.S1.16 and 71.22.S1.21 bindRobo4 endogenously expressed on HUVEC cells. FIGS. 18C and 18D show theresults of FACS plots indicating that the same affinity maturedanti-Robo4 antibody clones bind murine Robo4 on the endogenouslyexpressed on murine MS1 cells. These plots also show that the parentantibody, 71.22, also cross-reacts with human and murine Robo4.

FIGS. 19A and 19B show that anti-Robo4 antibody 71.22 associates withvasculature following injection into mice as described in Example 12.

FIGS. 20A and 20B depict the results of a bead outgrowth assayindicating that anti-Robo4 antibody 71.22 inhibits HUVEC tubeelongation. FIG. 20A shows that both total number and length of tubesare reduced upon treatment of HUVECs with 71.22 as compared to anirrelevant control antibody (anti-ragweed, E25). Anti-VEGF was used aspositive control antibody. FIG. 20B shows representative examples withconcentric circles drawn at 100, 200 and 300 μm.

DETAILED DESCRIPTION OF THE INVENTION I. Introduction

The present invention provides compositions that bind Robo4 or a portionthereof, kits and articles of manufacture comprising such compositions,and methods of using such compositions, including, e.g., methods formodulating ligand binding to the Robo4 receptor and for modulatingbiological/physiological activities associated with ligand binding tothe Robo4 receptor. The invention is based in part on the identificationof a variety of anti-Robo4 antibodies that bind the Robo4 receptor, areceptor useful as a therapeutic and diagnostic (e.g., in vivo, invitro, or ex vivo imaging) target. The anti-Robo4 antibodies of theinvention can conveniently be used as therapeutic and diagnostic agentsfor use in targeting pathological conditions associated with abnormal orunwanted endothelial cell proliferation, such as abnormal or unwantedvascular cell proliferation in disorders including, but not limited to,cancer, dysregulated angiogenesis and disorders associated with (e.g.,augmented by) endothelial cell proliferation within the tissueexperiencing the disorder, solid tumors and metastasis, atherosclerosis,retrolental fibroplasia, hemangiomas, chronic inflammation, intraocularneovascular diseases such as proliferative retinopathies, e.g., diabeticretinopathy, age-related macular degeneration (AMD), neovascularglaucoma, immune rejection of transplanted corneal tissue and othertissues, rheumatoid arthritis, and psoriasis. The anti-Robo4 antibodiesof the invention can be used alone or in combination with additionalagents (including anti-neoplastic compositions, chemotherapeutic agents,cytotoxic agents, growth-inhibitory agents. In some embodiments, theinvention provides methods for identifying and/or using Robo4-targetedantibodies to block Robo4 function, deliver cytotoxic agents to cellsexpressing Robo4 (e.g., on the cell surface), and/or deliver imagingagents to cells expressing Robo4 on the cell surface. For example, insome embodiments, detectably labeled anti-Robo4 antibodies canconveniently be used as an imaging agent for disease states in whichincreased vascularization is harmful (e.g. cancer and maculardegeneration) or for physiological conditions in which endothelial cellproliferation, vascular cell proliferation, and/or angiogenesis is adesirable condition (such as in, for example, wound healing).

II. Definitions

As used herein, the following terms have the meanings ascribed to thembelow unless otherwise specified.

The term “Robo4” or “Magic Roundabout,” “Endothelial Cell-SpecificMolecule 4,” or “ECSM4” as used herein refers to any native or variant(whether native or synthetic) Robo4 polypeptide comprising the aminoacid sequence shown in FIG. 5, a variant or a subsequence thereof towhich the antibody of the present invention specifically binds,including, e.g., the extracellular domain of Robo4 or any subsequencethereof. The term “wild type Robo4” generally refers to a polypeptidecomprising the amino acid sequence of a naturally occurring Robo4protein. The term “wild type Robo4 sequence” generally refers to anamino acid sequence found in a naturally occurring Robo4. The Robo4polypeptide of the invention is a mammalian Robo4 polypeptide, such as,without limitation human, equine, bovine, porcine, canine, feline,rodent Robo4. “Robo4,” “Magic Roundabout,” “Endothelial Cell-SpecificMolecule 4,” or “ECSM4” also refer to nucleic acids and polypeptidepolymorphic variants, alleles, mutants, and interspecies homologs that:(1) have an amino acid sequence that has greater than about 60% aminoacid sequence identity, 65%, 70%, 75%, 80%, 85%, 90%, preferably 91%,92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% or greater amino acid sequenceidentity, preferably over a region of at least about 25, 50, 100, 200,500, 1000, or more amino acids, to an amino acid sequence encoded by aRobo4 nucleic acid (for a human Robo4 polypeptide sequence, see, e.g.,FIGS. 5 and 7 and SEQ ID NOS:138 and 171; for a murine Robo4 polypeptidesequence, see, e.g., SEQ ID NO:172); (2) bind to antibodies, e.g.,polyclonal antibodies and/or monoclonal antibodies, raised against animmunogen comprising an amino acid sequence of a Robo4 protein, andconservatively modified variants thereof; (3) specifically hybridizeunder stringent hybridization conditions to an anti-sense strandcorresponding to a nucleic acid sequence encoding a Robo4 protein, andconservatively modified variants thereof, (4) have a nucleic acidsequence that has greater than about 95%, preferably greater than about96%, 97%, 98%, 99%, or higher nucleotide sequence identity, preferablyover a region of at least about 25, 50, 100, 200, 500, 1000, or morenucleotides, to a Robo4 nucleic acid (e.g., a nucleic acid encoding thepolypeptide set forth in FIGS. 5 and 7 and SEQ ID NOS:138, 171, or 172.Preferably the Robo4 nucleic acid has greater than 80%, 85%, 90%, 95%,96%, 97%, 98%, or 99% identity to the nucleic acid sequence encoding SEQID NOS:138, 171, or 172, preferably over a region of at least about 25,50, 100, 150, 200, 250, 300, 350, 400, 450, or 500, 600, 700, 800, 900,or 1000 or more nucleotides.

The term “anti-Robo4 antibody” or “an antibody that binds to Robo4”refers to an antibody that is capable of binding Robo4 with sufficientaffinity such that the antibody is useful as a diagnostic and/ortherapeutic agent in targeting Robo4. Preferably, the extent of bindingof an anti-Robo4 antibody to an unrelated, non-Robo4 protein is lessthan about 10% of the binding of the antibody to Robo4 as measured,e.g., by a radioimmunoassay (RIA). In certain embodiments, an antibodythat binds to Robo4 has a dissociation constant (Kd) of ≦1 μM, ≦100 nM,≦10 nM, ≦1 nM, or ≦0.1 nM. In certain embodiments, an anti-Robo4antibody binds to an epitope of Robo4 that is conserved among Robo4 fromdifferent species. In other embodiments, an ant-Robo4 antibody binds toan epitope of Robo4 that is not conserved among Robo4 from differentspecies.

The term “antibody” herein is used in the broadest sense andspecifically covers monoclonal antibodies, polyclonal antibodies,multispecific antibodies (e.g. bispecific antibodies) formed from atleast two intact antibodies, and antibody fragments so long as theyexhibit the desired biological activity.

An “isolated” antibody is one which has been identified and separatedand/or recovered from a component of its natural environment.Contaminant components of its natural environment are materials whichwould interfere with research, diagnostic or therapeutic uses for theantibody, and may include enzymes, hormones, and other proteinaceous ornonproteinaceous solutes. In some embodiments, an antibody is purified(1) to greater than 95% by weight of antibody as determined by, forexample, the Lowry method, and in some embodiments, to greater than 99%by weight; (2) to a degree sufficient to obtain at least 15 residues ofN-terminal or internal amino acid sequence by use of, for example, aspinning cup sequenator, or (3) to homogeneity by SDS-PAGE underreducing or nonreducing conditions using, for example, Coomassie blue orsilver stain. Isolated antibody includes the antibody in situ withinrecombinant cells since at least one component of the antibody's naturalenvironment will not be present. Ordinarily, however, isolated antibodywill be prepared by at least one purification step.

“Native antibodies” are usually heterotetrameric glycoproteins of about150,000 daltons, composed of two identical light (L) chains and twoidentical heavy (H) chains. Each light chain is linked to a heavy chainby one covalent disulfide bond, while the number of disulfide linkagesvaries among the heavy chains of different immunoglobulin isotypes. Eachheavy and light chain also has regularly spaced intrachain disulfidebridges. Each heavy chain has at one end a variable domain (V_(H))followed by a number of constant domains. Each light chain has avariable domain at one end (V_(L)) and a constant domain at its otherend; the constant domain of the light chain is aligned with the firstconstant domain of the heavy chain, and the light chain variable domainis aligned with the variable domain of the heavy chain. Particular aminoacid residues are believed to form an interface between the light chainand heavy chain variable domains.

The “variable region” or “variable domain” of an antibody refers to theamino-terminal domains of the heavy or light chain of the antibody. Thevariable domain of the heavy chain may be referred to as “VH.” Thevariable domain of the light chain may be referred to as “VL.” Thesedomains are generally the most variable parts of an antibody and containthe antigen-binding sites.

The term “variable” refers to the fact that certain portions of thevariable domains differ extensively in sequence among antibodies and areused in the binding and specificity of each particular antibody for itsparticular antigen. However, the variability is not evenly distributedthroughout the variable domains of antibodies. It is concentrated inthree segments called hypervariable regions (HVRs) both in thelight-chain and the heavy-chain variable domains. The more highlyconserved portions of variable domains are called the framework regions(FR). The variable domains of native heavy and light chains eachcomprise four FR regions, largely adopting a beta-sheet configuration,connected by three HVRs, which form loops connecting, and in some casesforming part of, the beta-sheet structure. The HVRs in each chain areheld together in close proximity by the FR regions and, with the HVRsfrom the other chain, contribute to the formation of the antigen-bindingsite of antibodies (see Kabat et al., Sequences of Proteins ofImmunological Interest, Fifth Edition, National Institute of Health,Bethesda, Md. (1991)). The constant domains are not involved directly inthe binding of an antibody to an antigen, but exhibit various effectorfunctions, such as participation of the antibody in antibody-dependentcellular toxicity.

The “light chains” of antibodies (immunoglobulins) from any vertebratespecies can be assigned to one of two clearly distinct types, calledkappa (κ) and lambda (λ), based on the amino acid sequences of theirconstant domains.

Depending on the amino acid sequences of the constant domains of theirheavy chains, antibodies (immunoglobulins) can be assigned to differentclasses. There are five major classes of immunoglobulins: IgA, IgD, IgE,IgG, and IgM, and several of these may be further divided intosubclasses (isotypes), e.g., IgG₁, IgG₂, IgG₃, IgG₄, IgA₁, and IgA₂. Theheavy chain constant domains that correspond to the different classes ofimmunoglobulins are called α, δ, ε, γ, and μ, respectively. The subunitstructures and three-dimensional configurations of different classes ofimmunoglobulins are well known and described generally in, for example,Abbas et al. Cellular and Mol. Immunology, 4th ed. (W.B. Saunders, Co.,2000). An antibody may be part of a larger fusion molecule, formed bycovalent or non-covalent association of the antibody with one or moreother proteins or peptides.

The terms “full length antibody,” “intact antibody” and “whole antibody”are used herein interchangeably to refer to an antibody in itssubstantially intact form, not antibody fragments as defined below. Theterms particularly refer to an antibody with heavy chains that containan Fc region.

A “naked antibody” for the purposes herein is an antibody that is notconjugated to a cytotoxic moiety or radiolabel.

“Antibody fragments” comprise a portion of an intact antibody,preferably comprising the antigen binding region thereof. Examples ofantibody fragments include Fab, Fab′, F(ab′)₂, and Fv fragments;diabodies; linear antibodies; single-chain antibody molecules; andmultispecific antibodies formed from antibody fragments.

Papain digestion of antibodies produces two identical antigen-bindingfragments, called “Fab” fragments, each with a single antigen-bindingsite, and a residual “Fc” fragment, whose name reflects its ability tocrystallize readily. Pepsin treatment yields an F(ab′)₂ fragment thathas two antigen-combining sites and is still capable of cross-linkingantigen.

“Fv” is the minimum antibody fragment which contains a completeantigen-binding site. In one embodiment, a two-chain Fv species consistsof a dimer of one heavy- and one light-chain variable domain in tight,non-covalent association. In a single-chain Fv (scFv) species, oneheavy- and one light-chain variable domain can be covalently linked by aflexible peptide linker such that the light and heavy chains canassociate in a “dimeric” structure analogous to that in a two-chain Fvspecies. It is in this configuration that the three HVRs of eachvariable domain interact to define an antigen-binding site on thesurface of the VH-VL dimer. Collectively, the six HVRs conferantigen-binding specificity to the antibody. However, even a singlevariable domain (or half of an Fv comprising only three HVRs specificfor an antigen) has the ability to recognize and bind antigen, althoughat a lower affinity than the entire binding site.

The Fab fragment contains the heavy- and light-chain variable domainsand also contains the constant domain of the light chain and the firstconstant domain (CH1) of the heavy chain. Fab′ fragments differ from Fabfragments by the addition of a few residues at the carboxy terminus ofthe heavy chain CH1 domain including one or more cysteines from theantibody hinge region. Fab′-SH is the designation herein for Fab′ inwhich the cysteine residue(s) of the constant domains bear a free thiolgroup. F(ab′)₂ antibody fragments originally were produced as pairs ofFab′ fragments which have hinge cysteines between them. Other chemicalcouplings of antibody fragments are also known.

“Single-chain Fv” or “scFv” antibody fragments comprise the VH and VLdomains of antibody, wherein these domains are present in a singlepolypeptide chain. Generally, the scFv polypeptide further comprises apolypeptide linker between the VH and VL domains which enables the scFvto form the desired structure for antigen binding. For a review of scFv,see, e.g., Pluckthün, in The Pharmacology of Monoclonal Antibodies, vol.113, Rosenburg and Moore eds., (Springer-Verlag, New York, 1994), pp.269-315.

The term “diabodies” refers to antibody fragments with twoantigen-binding sites, which fragments comprise a heavy-chain variabledomain (VH) connected to a light-chain variable domain (VL) in the samepolypeptide chain (VH-VL). By using a linker that is too short to allowpairing between the two domains on the same chain, the domains areforced to pair with the complementary domains of another chain andcreate two antigen-binding sites. Diabodies may be bivalent orbispecific. Diabodies are described more fully in, for example, EP404,097; WO 1993/01161; Hudson et al., Nat. Med. 9:129-134 (2003); andHollinger et al., PNAS USA 90: 6444-6448 (1993). Triabodies andtetrabodies are also described in Hudson et al., Nat. Med. 9:129-134(2003).

The term “monoclonal antibody” as used herein refers to an antibodyobtained from a population of substantially homogeneous antibodies,i.e., the individual antibodies comprising the population are identicalexcept for possible mutations, e.g., naturally occurring mutations, thatmay be present in minor amounts. Thus, the modifier “monoclonal”indicates the character of the antibody as not being a mixture ofdiscrete antibodies. In certain embodiments, such a monoclonal antibodytypically includes an antibody comprising a polypeptide sequence thatbinds a target, wherein the target-binding polypeptide sequence wasobtained by a process that includes the selection of a single targetbinding polypeptide sequence from a plurality of polypeptide sequences.For example, the selection process can be the selection of a uniqueclone from a plurality of clones, such as a pool of hybridoma clones,phage clones, or recombinant DNA clones. It should be understood that aselected target binding sequence can be further altered, for example, toimprove affinity for the target, to humanize the target bindingsequence, to improve its production in cell culture, to reduce itsimmunogenicity in vivo, to create a multispecific antibody, etc., andthat an antibody comprising the altered target binding sequence is alsoa monoclonal antibody of this invention. In contrast to polyclonalantibody preparations, which typically include different antibodiesdirected against different determinants (epitopes), each monoclonalantibody of a monoclonal antibody preparation is directed against asingle determinant on an antigen. In addition to their specificity,monoclonal antibody preparations are advantageous in that they aretypically uncontaminated by other immunoglobulins.

The modifier “monoclonal” indicates the character of the antibody asbeing obtained from a substantially homogeneous population ofantibodies, and is not to be construed as requiring production of theantibody by any particular method. For example, the monoclonalantibodies to be used in accordance with the present invention may bemade by a variety of techniques, including, for example, the hybridomamethod (e.g., Kohler and Milstein, Nature, 256:495-97 (1975); Hongo etal., Hybridoma, 14 (3): 253-260 (1995), Harlow et al., Antibodies: ALaboratory Manual, (Cold Spring Harbor Laboratory Press, 2nd ed. 1988);Hammerling et al., in: Monoclonal Antibodies and T-Cell Hybridomas563-681 (Elsevier, N.Y., 1981)), recombinant DNA methods (see, e.g.,U.S. Pat. No. 4,816,567), phage-display technologies (see, e.g.,Clackson et al., Nature, 352: 624-628 (1991); Marks et al., J. Mol.Biol. 222: 581-597 (1992); Sidhu et al., J. Mol. Biol. 338(2): 299-310(2004); Lee et al., J. Mol. Biol. 340(5): 1073-1093 (2004); Fellouse,PNAS USA 101(34): 12467-12472 (2004); and Lee et al., J. Immunol.Methods 284(1-2): 119-132 (2004), and technologies for producing humanor human-like antibodies in animals that have parts or all of the humanimmunoglobulin loci or genes encoding human immunoglobulin sequences(see, e.g., WO 1998/24893; WO 1996/34096; WO 1996/33735; WO 1991/10741;Jakobovits et al., PNAS USA 90: 2551 (1993); Jakobovits et al., Nature362: 255-258 (1993); Bruggemann et al., Year in Immunol. 7:33 (1993);U.S. Pat. Nos. 5,545,807; 5,545,806; 5,569,825; 5,625,126; 5,633,425;and 5,661,016; Marks et al, Bio/Technology 10: 779-783 (1992); Lonberget al., Nature 368: 856-859 (1994); Morrison, Nature 368: 812-813(1994); Fishwild et al., Nature Biotechnol. 14: 845-851 (1996);Neuberger, Nature Biotechnol. 14: 826 (1996); and Lonberg and Huszar,Intern. Rev. Immunol. 13: 65-93 (1995).

The monoclonal antibodies herein specifically include “chimeric”antibodies in which a portion of the heavy and/or light chain isidentical with or homologous to corresponding sequences in antibodiesderived from a particular species or belonging to a particular antibodyclass or subclass, while the remainder of the chain(s) is identical withor homologous to corresponding sequences in antibodies derived fromanother species or belonging to another antibody class or subclass, aswell as fragments of such antibodies, so long as they exhibit thedesired biological activity (U.S. Pat. No. 4,816,567; and Morrison etal., PNAS USA 81:6851-6855 (1984)). Chimeric antibodies includePRIMATIZED® antibodies wherein the antigen-binding region of theantibody is derived from an antibody produced by, e.g., immunizingmacaque monkeys with the antigen of interest.

“Humanized” forms of non-human (e.g., murine) antibodies are chimericantibodies that contain minimal sequence derived from non-humanimmunoglobulin. For the most part, humanized antibodies are humanimmunoglobulins (recipient antibody) in which residues from ahypervariable region of the recipient are replaced by residues from ahypervariable region of a non-human species (donor antibody) such asmouse, rat, rabbit or nonhuman primate having the desired specificity,affinity, and capacity. In some instances, framework region (FR)residues of the human immunoglobulin are replaced by correspondingnon-human residues. Furthermore, humanized antibodies may compriseresidues that are not found in the recipient antibody or in the donorantibody. These modifications are made to further refine antibodyperformance. In general, the humanized antibody will comprisesubstantially all of at least one, and typically two, variable domains,in which all or substantially all of the hypervariable loops correspondto those of a non-human immunoglobulin and all or substantially all ofthe FRs are those of a human immunoglobulin sequence. The humanizedantibody optionally will also comprise at least a portion of animmunoglobulin constant region (Fc), typically that of a humanimmunoglobulin. For further details, see Jones et al., Nature321:522-525 (1986); Riechmann et al., Nature 332:323-329 (1988); andPresta, Curr. Op. Struct. Biol. 2:593-596 (1992). See also the followingreview articles and references cited therein: Vaswani and Hamilton, Ann.Allergy, Asthma & Immunol. 1:105-115 (1998); Harris, Biochem. Soc.Transactions 23:1035-1038 (1995); Hurle and Gross, Curr. Op. Biotech.5:428-433 (1994).

A “human antibody” is one which possesses an amino acid sequence whichcorresponds to that of an antibody produced by a human and/or has beenmade using any of the techniques for making human antibodies asdisclosed herein. This definition of a human antibody specificallyexcludes a humanized antibody comprising non-human antigen-bindingresidues. Human antibodies can be produced using various techniquesknown in the art, including phage-display libraries. Hoogenboom andWinter, J. Mol. Biol., 227:381 (1991); Marks et al., J. Mol. Biol.,222:581 (1991). Also available for the preparation of human monoclonalantibodies are methods described in Cole et al., Monoclonal Antibodiesand Cancer Therapy, Alan R. Liss, p. 77 (1985); Boerner et al., J.Immunol., 147(1):86-95 (1991). See also van Dijk and van de Winkel,Curr. Opin. Pharmacol., 5: 368-74 (2001). Human antibodies can beprepared by administering the antigen to a transgenic animal that hasbeen modified to produce such antibodies in response to antigenicchallenge, but whose endogenous loci have been disabled, e.g., immunizedxenomice (see, e.g., U.S. Pat. Nos. 6,075,181 and 6,150,584 regardingXENOMOUSE™ technology). See also, for example, Li et al., PNAS USA,103:3557-3562 (2006) regarding human antibodies generated via a humanB-cell hybridoma technology.

An “antigen” is a predetermined antigen (e.g. a Robo4 sequence) to whichan antibody can selectively bind. The target antigen may be polypeptide,carbohydrate, nucleic acid, lipid, hapten or other naturally occurringor synthetic compound. Preferably, the target antigen is a polypeptide.

An “acceptor human framework” for the purposes herein is a frameworkcomprising the amino acid sequence of a VL or VH framework derived froma human immunoglobulin framework, or from a human consensus framework.An acceptor human framework “derived from” a human immunoglobulinframework or human consensus framework may comprise the same amino acidsequence thereof, or may contain pre-existing amino acid sequencechanges. In some embodiments, the number of pre-existing amino acidchanges are 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, 5 orless, 4 or less, 3 or less, or 2 or less. Where pre-existing amino acidchanges are present in a VH, preferably those changes occur at onlythree, two, or one of positions 71H, 73H and 78H; for instance, theamino acid residues at those positions may be 71A, 73T and/or 78A. Inone embodiment, the VL acceptor human framework is identical in sequenceto the VL human immunoglobulin framework sequence or human consensusframework sequence. Where pre-existing amino acid changes are present ina VH, preferably those changes are only at three, two or one ofpositions 71H, 73H and 78H; for instance, the amino acid residues atthose positions may be 71A, 73T and/or 78A. In one embodiment, the VLacceptor human framework is identical in sequence to the VL humanimmunoglobulin framework sequence or human consensus framework sequence.

A “human consensus framework” is a framework which represents the mostcommonly occurring amino acid residue in a selection of humanimmunoglobulin VL or VH framework sequences. Generally, the selection ofhuman immunoglobulin VL or VH sequences is from a subgroup of variabledomain sequences. Generally, the subgroup of sequences is a subgroup asin Kabat et al. In one embodiment, for the VL, the subgroup is subgroupkappa I as in Kabat et al. In one embodiment, for the VH, the subgroupis subgroup III as in Kabat et al.

A “VH subgroup III consensus framework” comprises the consensus sequenceobtained from the amino acid sequences in variable heavy subgroup III ofKabat et al. In one embodiment, the VH subgroup III consensus frameworkamino acid sequence comprises at least a portion or all of each of thefollowing sequences: EVQLVESGGGLVQPGGSLRLSCAAS (SEQ IDNO:128)-H1-WVRQAPGKGLEWV (SEQ IDNO:129)-H2-RFTISRDNSKNTLYLQMNSLRAEDTAVYYC (SEQ ID NO:131)-H3-WGQGTLVTVSS(SEQ ID NO:16). In another embodiment, the VH subgroup III consensusframework amino acid sequence comprises at least a portion or all ofeach of the following sequences: EVQLVESGGGLVQPGGSLRLSCAAS (SEQ IDNO:128)-H1-WVRQAPGKGLEWV (SEQ IDNO:129)-H2-RFTISADTSKNTAYLQMNSLRLRAEDTAVYYC (SEQ IDNO:137)-H3-WGQGTLVTVSS (SEQ ID NO:16)

A “VL subgroup I consensus framework” comprises the consensus sequenceobtained from the amino acid sequences in variable light kappa subgroupI of Kabat et al. In one embodiment, the VH subgroup I consensusframework amino acid sequence comprises at least a portion or all ofeach of the following sequences:

DIQMTQSPSSLSASVGDRVTITC (SEQ ID NO: 9) -L1-WYQQKPGKAPKLLIY(SEQ ID NO: 10) -L2-VPSRFSGSGSGTDFTLTISSLQPEDFATYYC (SEQ ID NO: 99)-L3-FGQGTKVEIK. (SEQ ID NO: 100)

An “unmodified human framework” is a human framework which has the sameamino acid sequence as the acceptor human framework, e.g. lacking humanto non-human amino acid substitution(s) in the acceptor human framework.

The term “hypervariable region”, “HVR”, or “HV”, when used herein refersto the regions of an antibody variable domain which are hypervariable insequence and/or form structurally defined loops. Generally, antibodiescomprise six hypervariable regions; three in the VH (H1, H2, H3), andthree in the VL (L1, L2, L3). A number of hypervariable regiondelineations are in use and are encompassed herein. The KabatComplementarity Determining Regions (CDRs) are HVRs that are based onsequence variability and are the most commonly used (Kabat et al.,Sequences of Proteins of Immunological Interest, 5th Ed. Public HealthService, National Institutes of Health, Bethesda, Md. (1991)). Chothiarefers instead to the location of the structural loops (Chothia and LeskJ. Mol. Biol. 196:901-917 (1987)). The AbM hypervariable regionsrepresent a compromise between the Kabat CDRs and Chothia structuralloops, and are used by Oxford Molecular's AbM antibody modelingsoftware. The “contact” hypervariable regions are based on an analysisof the available complex crystal structures. The residues from each ofthese hypervariable regions are noted below.

Loop Kabat AbM Chothia Contact L1 L24-L34 L24-L34 L26-L32 L30-L36 L2L50-L56 L50-L56 L50-L52 L46-L55 L3 L89-L97 L89-L97 L91-L96 L89-L96 H1H31-H35B H26-H35B H26-H32 H30-H35B (Kabat Numbering) H1 H31-H35 H26-H35H26-H32 H30-H35 (Chothia Numbering) H2 H50-H65 H50-H58 H53-H55 H47-H58H3 H95-H102 H95-H102 H96-H101 H93-H101

The amino acid position/boundary delineating a hypervariable region ofan antibody can vary, depending on the context and the variousdefinitions known in the art (as described below). Some positions withina variable domain may be viewed as hybrid hypervariable positions inthat these positions can be deemed to be within a hypervariable regionunder one set of criteria while being deemed to be outside ahypervariable region under a different set of criteria. One or more ofthese positions can also be found in extended hypervariable regions. Inone embodiment, these hybrid hypervariable positions include one or moreof positions 26-30, 26-35 33-35B, 47-49, 49-65, 57-65, 95-102, 93, 94and 102 in a heavy chain variable domain. In one embodiment, thesehybrid hypervariable positions include one or more of positions 24-29,24-34, 35-36, 46-49, 50-56, 89-97, 56 and 97 in a light chain variabledomain.

As used herein, the HVRs of the light chain are referred tointerchangeably as HVR-L1, -L2, or -L3, or HVR1-LC, HVR2-LC or HVR3-LCor other similar designation that indicates that a light chain HVR isreferenced. As used herein, the HVRs of the heavy chain are referred tointerchangeably as HVR-H1, -H2, or -H3, or HVR1-HC, HVR2-HC, or HVR3-HC,or other similar designation that indicates that a heavy chain HVR isreferenced.

Hypervariable regions may comprise “extended hypervariable regions” asfollows: 24-36 or 24-34 (L1), 46-56 or 50-56 (L2) and 89-97 (L3) in theVL and 26-35 (H1), 50-65 or 49-65 (H2) and 93-102, 94-102 or 95-102 (H3)in the VH. The variable domain residues are numbered according to Kabatet al., supra for each of these definitions.

An “altered hypervariable region” for the purposes herein is ahypervariable region comprising one or more (e.g. one to about 16) aminoacid substitution(s) therein.

An “un-modified hypervariable region” for the purposes herein is ahypervariable region having the same amino acid sequence as a non-humanantibody from which it was derived, i.e. one which lacks one or moreamino acid substitutions therein.

“Framework” or “FR” residues are those variable domain residues otherthan the hypervariable region residues as herein defined. As usedherein, LC-FR1-4 or FR1-4-LC or similar designation is usedinterchangeably and refers to framework regions of the light chain. Asused herein, HC-FR1-4 or FR1-4-HC or similar designation is usedinterchangeably and refers to framework region of the heavy chain.

An “affinity matured” antibody is one with one or more alterations inone or more CDRs thereof which result in an improvement in the affinityof the antibody for antigen, compared to a parent antibody which doesnot possess those alteration(s). Preferred affinity matured antibodieswill have nanomolar or even picomolar affinities for the target antigen.Affinity matured antibodies are produced by procedures known in the art.Marks et al., Bio/Technology 10:779-783 (1992) describes affinitymaturation by VH and VL domain shuffling. Random mutagenesis of CDRand/or framework residues is described by: Barbas et al., PNAS USA91:3809-3813 (1994); Schier et al., Gene 169:147-155 (1995); Yelton etal., J. Immunol. 155:1994-2004 (1995); Jackson et al., J. Immunol.154(7):3310-9 (1995); and Hawkins et al, J. Mol. Biol. 226:889-896(1992).

A “blocking” antibody or an “antagonist” antibody is one which inhibitsor reduces biological activity of the antigen it binds. For exampleblocking antibodies or antagonist anti-Robo4 antibodies substantially orcompletely inhibit the angiogenesis by binding Robo4.

The term “variable domain residue numbering as in Kabat” or “amino acidposition numbering as in Kabat”, and variations thereof, refers to thenumbering system used for heavy chain variable domains or light chainvariable domains of the compilation of antibodies in Kabat et al.,Sequences of Proteins of Immunological Interest, 5th Ed. Public HealthService, National Institutes of Health, Bethesda, Md. (1991). Using thisnumbering system, the actual linear amino acid sequence may containfewer or additional amino acids corresponding to a shortening of, orinsertion into, a FR or CDR of the variable domain. For example, a heavychain variable domain may include a single amino acid insert (residue52a according to Kabat) after residue 52 of H2 and inserted residues(e.g. residues 82a, 82b, and 82c, etc according to Kabat) after heavychain FR residue 82. The Kabat numbering of residues may be determinedfor a given antibody by alignment at regions of homology of the sequenceof the antibody with a “standard” Kabat numbered sequence.

The phrase “substantially similar,” or “substantially the same”, as usedherein, denotes a sufficiently high degree of similarity between twonumeric values (generally one associated with an antibody of theinvention and the other associated with a reference/comparator antibody)such that one of skill in the art would consider the difference betweenthe two values to be of little or no biological and/or statisticalsignificance within the context of the biological characteristicmeasured by said values (e.g., Kd values). The difference between saidtwo values is preferably less than about 50%, preferably less than about40%, preferably less than about 30%, preferably less than about 20%,preferably less than about 10% as a function of the value for thereference/comparator antibody.

“Binding affinity” generally refers to the strength of the sum total ofnoncovalent interactions between a single binding site of a molecule(e.g., an antibody) and its binding partner (e.g., an antigen). Unlessindicated otherwise, as used herein, “binding affinity” refers tointrinsic binding affinity which reflects a 1:1 interaction betweenmembers of a binding pair (e.g., antibody and antigen). The affinity ofa molecule X for its partner Y can generally be represented by thedissociation constant (K_(d)). Affinity can be measured by commonmethods known in the art, including those described herein. Low-affinityantibodies generally bind antigen slowly and tend to dissociate readily,whereas high-affinity antibodies generally bind antigen faster and tendto remain bound longer. A variety of methods of measuring bindingaffinity are known in the art, any of which can be used for purposes ofthe present invention. Specific illustrative embodiments are describedin the following.

In one embodiment, the “K_(d),” “K_(D),” or “K_(d) value,” is measuredby a radiolabeled antigen binding assay (RIA) performed with the Fabversion of an antibody of interest and its antigen as described by thefollowing assay that measures solution binding affinity of Fabs forantigen by equilibrating Fab with a minimal concentration of(¹²⁵I)-labeled antigen in the presence of a titration series ofunlabeled antigen, then capturing bound antigen with an anti-Fabantibody-coated plate (Chen, et al., (1999) J. Mol Biol 293:865-881). Toestablish conditions for the assay, microtiter plates (Dynex) are coatedovernight with 5 ug/ml of a capturing anti-Fab antibody (Cappel Labs) in50 mM sodium carbonate (pH 9.6), and subsequently blocked with 2% (w/v)bovine serum albumin in PBS for two to five hours at room temperature(approximately 23° C.). In a non-adsorbant plate (Nunc #269620), 100 pMor 26 pM [¹²⁵I]-antigen are mixed with serial dilutions of a Fab ofinterest (e.g., Fab-12 as described in Presta et al., Cancer Res.57:4593-4599 (1997)). The Fab of interest is then incubated overnight;however, the incubation may continue for a longer period (e.g., 65hours) to insure that equilibrium is reached. Thereafter, the mixturesare transferred to the capture plate for incubation at room temperature(e.g., for one hour). The solution is then removed and the plate washedeight times with 0.1% Tween® 20 in PBS. When the plates have dried, 150ul/well of scintillant (MicroScint-20; Packard) is added, and the platesare counted on a Topcount gamma counter (Packard) for ten minutes.Concentrations of each Fab that give less than or equal to 20% ofmaximal binding are chosen for use in competitive binding assays.According to another embodiment the Kd or Kd value is measured by usingsurface plasmon resonance assays using a BIAcore™-2000 or aBIAcore™-3000 (BIAcore, Inc., Piscataway, N.J.) at 25° C. withimmobilized antigen CM5 chips at ˜10 response units (RU). Briefly,carboxymethylated dextran biosensor chips (CM5, BIAcore Inc.) areactivated with N-ethyl-N′-(3-dimethylaminopropyl)-carbodiimidehydrochloride (EDC) and N-hydroxysuccinimide (NHS) according to thesupplier's instructions. Antigen is diluted with 10 mM sodium acetate,pH 4.8, into 5 ug/ml (˜0.2 uM) before injection at a flow rate of 5ul/minute to achieve approximately 10 response units (RU) of coupledprotein. Following the injection of antigen, 1M ethanolamine is injectedto block unreacted groups. For kinetics measurements, two-fold serialdilutions of Fab (0.78 nM to 500 nM) are injected in PBS with 0.05%Tween® 20 (PBST) at 25° C. at a flow rate of approximately 25 ul/min.Association rates (k_(on)) and dissociation rates (k_(off)) arecalculated using a simple one-to-one Langmuir binding model (BIAcoreEvaluation Software version 3.2) by simultaneous fitting the associationand dissociation sensorgram. The equilibrium dissociation constant(K_(d)) is calculated as the ratio k_(off)/k_(on). See, e.g., Chen etal., J. Mol. Biol 293:865-881 (1999). If the on-rate exceeds 10⁶ M⁻¹S⁻¹by the surface plasmon resonance assay above, then the on-rate can bedetermined by using a fluorescent quenching technique that measures theincrease or decrease in fluorescence emission intensity (excitation=295nm; emission=340 nm, 16 nm band-pass) at 25° C. of a 20 nM anti-antigenantibody (Fab form) in PBS, pH 7.2, in the presence of increasingconcentrations of antigen as measured in a spectrometer, such as astop-flow equipped spectrophometer (Aviv Instruments) or a 8000-seriesSLM-Aminco™ spectrophotometer (ThermoSpectronic) with a stirred cuvette.

The phrase “substantially reduced,” or “substantially different”, asused herein, denotes a sufficiently high degree of difference betweentwo numeric values (generally one associated with an antibody of theinvention and the other associated with a reference/comparator antibody)such that one of skill in the art would consider the difference betweenthe two values to be of statistical significance within the context ofthe biological characteristic measured by said values (e.g., K_(d)values, HAMA response). The difference between said two values ispreferably greater than about 10%, preferably greater than about 20%,preferably greater than about 30%, preferably greater than about 40%,preferably greater than about 50% as a function of the value for thereference/comparator antibody.

“Percent (%) amino acid sequence identity” with respect to a peptide orpolypeptide sequence is defined as the percentage of amino acid residuesin a candidate sequence that are identical with the amino acid residuesin the specific peptide or polypeptide sequence, after aligning thesequences and introducing gaps, if necessary, to achieve the maximumpercent sequence identity, and not considering any conservativesubstitutions as part of the sequence identity. Alignment for purposesof determining percent amino acid sequence identity can be achieved invarious ways that are within the skill in the art, for instance, usingpublicly available computer software such as BLAST, BLAST-2, ALIGN orMegalign (DNASTAR™) software. Those skilled in the art can determineappropriate parameters for measuring alignment, including any algorithmsneeded to achieve maximal alignment over the full length of thesequences being compared. For purposes herein, however, % amino acidsequence identity values are generated using the sequence comparisoncomputer program ALIGN-2. The ALIGN-2 sequence comparison computerprogram was authored by Genentech, Inc. and the source code shown hasbeen filed with user documentation in the U.S. Copyright Office,Washington D.C., 20559, where it is registered under U.S. CopyrightRegistration No. TXU510087. The ALIGN-2 program is publicly availablethrough Genentech, Inc., South San Francisco, Calif. The ALIGN-2 programshould be compiled for use on a UNIX operating system, preferablydigital UNIX V4.0D. All sequence comparison parameters are set by theALIGN-2 program and do not vary.

In situations where ALIGN-2 is employed for amino acid sequencecomparisons, the % amino acid sequence identity of a given amino acidsequence A to, with, or against a given amino acid sequence B (which canalternatively be phrased as a given amino acid sequence A that has orcomprises a certain % amino acid sequence identity to, with, or againsta given amino acid sequence B) is calculated as follows:

100 times the fraction X/Y

where X is the number of amino acid residues scored as identical matchesby the sequence alignment program ALIGN-2 in that program's alignment ofA and B, and where Y is the total number of amino acid residues in B. Itwill be appreciated that where the length of amino acid sequence A isnot equal to the length of amino acid sequence B, the % amino acidsequence identity of A to B will not equal the % amino acid sequenceidentity of B to A.

Unless specifically stated otherwise, all % amino acid sequence identityvalues used herein are obtained as described in the immediatelypreceding paragraph using the ALIGN-2 computer program.

The term “vector,” as used herein, is intended to refer to a nucleicacid molecule capable of transporting another nucleic acid to which ithas been linked. One type of vector is a “plasmid”, which refers to acircular double stranded DNA loop into which additional DNA segments maybe ligated. Another type of vector is a phage vector. Another type ofvector is a viral vector, wherein additional DNA segments may be ligatedinto the viral genome. Certain vectors are capable of autonomousreplication in a host cell into which they are introduced (e.g.,bacterial vectors having a bacterial origin of replication and episomalmammalian vectors). Other vectors (e.g., non-episomal mammalian vectors)can be integrated into the genome of a host cell upon introduction intothe host cell, and thereby are replicated along with the host genome.Moreover, certain vectors are capable of directing the expression ofgenes to which they are operatively linked. Such vectors are referred toherein as “recombinant expression vectors” (or simply, “recombinantvectors”). In general, expression vectors of utility in recombinant DNAtechniques are often in the form of plasmids. In the presentspecification, “plasmid” and “vector” may be used interchangeably as theplasmid is the most commonly used form of vector.

“Polynucleotide,” or “nucleic acid,” as used interchangeably herein,refer to polymers of nucleotides of any length, and include DNA and RNA.The nucleotides can be deoxyribonucleotides, ribonucleotides, modifiednucleotides or bases, and/or their analogs, or any substrate that can beincorporated into a polymer by DNA or RNA polymerase, or by a syntheticreaction. A polynucleotide may comprise modified nucleotides, such asmethylated nucleotides and their analogs. If present, modification tothe nucleotide structure may be imparted before or after assembly of thepolymer. The sequence of nucleotides may be interrupted bynon-nucleotide components. A polynucleotide may be further modifiedafter synthesis, such as by conjugation with a label. Other types ofmodifications include, for example, “caps,” substitution of one or moreof the naturally occurring nucleotides with an analog, internucleotidemodifications such as, for example, those with uncharged linkages (e.g.,methyl phosphonates, phosphotriesters, phosphoamidates, carbamates,etc.) and with charged linkages (e.g., phosphorothioates,phosphorodithioates, etc.), those containing pendant moieties, such as,for example, proteins (e.g., nucleases, toxins, antibodies, signalpeptides, poly-L-lysine, etc.), those with intercalators (e.g.,acridine, psoralen, etc.), those containing chelators (e.g., metals,radioactive metals, boron, oxidative metals, etc.), those containingalkylators, those with modified linkages (e.g., alpha anomeric nucleicacids, etc.), as well as unmodified forms of the polynucleotide(s).Further, any of the hydroxyl groups ordinarily present in the sugars maybe replaced, for example, by phosphonate groups, phosphate groups,protected by standard protecting groups, or activated to prepareadditional linkages to additional nucleotides, or may be conjugated tosolid or semi-solid supports. The 5′ and 3′ terminal OH can bephosphorylated or substituted with amines or organic capping groupmoieties of from 1 to 20 carbon atoms. Other hydroxyls may also bederivatized to standard protecting groups. Polynucleotides can alsocontain analogous forms of ribose or deoxyribose sugars that aregenerally known in the art, including, for example, 2′-O-methyl-,2′-O-allyl, 2′-fluoro- or 2′-azido-ribose, carbocyclic sugar analogs,α-anomeric sugars, epimeric sugars such as arabinose, xyloses orlyxoses, pyranose sugars, furanose sugars, sedoheptuloses, acyclicanalogs and abasic nucleoside analogs such as methyl riboside. One ormore phosphodiester linkages may be replaced by alternative linkinggroups. These alternative linking groups include, but are not limitedto, embodiments wherein phosphate is replaced by P(O)S (“thioate”),P(S)S (“dithioate”), “(O)NR₂ (“amidate”), P(O)R, P(O)OR′, CO or CH₂(“formacetal”), in which each R or R′ is independently H or substitutedor unsubstituted alkyl (1-20 C.) optionally containing an ether (—O—)linkage, aryl, alkenyl, cycloalkyl, cycloalkenyl or araldyl. Not alllinkages in a polynucleotide need be identical. The precedingdescription applies to all polynucleotides referred to herein, includingRNA and DNA.

“Oligonucleotide,” as used herein, generally refers to short, generallysingle stranded, generally synthetic polynucleotides that are generally,but not necessarily, less than about 200 nucleotides in length. Theterms “oligonucleotide” and “polynucleotide” are not mutually exclusive.The description above for polynucleotides is equally and fullyapplicable to oligonucleotides.

A “disorder” or “disease” is any condition that would benefit fromtreatment with a substance/molecule or method of the invention. Thisincludes chronic and acute disorders or diseases including thosepathological conditions which predispose the mammal to the disorder inquestion. Non-limiting examples of disorders to be treated hereininclude malignant and benign tumors; non-leukemias and lymphoidmalignancies; neuronal, glial, astrocytal, hypothalamic and otherglandular, macrophagal, epithelial, stromal and blastocoelic disorders;and inflammatory, immunologic and other angiogenesis-related disorders.

The terms “cell proliferative disorder” and “proliferative disorder”refer to disorders that are associated with some degree of abnormal cellproliferation. In one embodiment, the cell proliferative disorder iscancer. In one embodiment, the cell proliferative disorder isangiogenesis.

“Tumor”, as used herein, refers to all neoplastic cell growth andproliferation, whether malignant or benign, and all pre-cancerous andcancerous cells and tissues. The terms “cancer”, “cancerous”, “cellproliferative disorder”, “proliferative disorder” and “tumor” are notmutually exclusive as referred to herein.

The terms “cancer” and “cancerous” refer to or describe thephysiological condition in mammals that is typically characterized byunregulated cell proliferation. Examples of cancer include but are notlimited to, carcinoma, lymphoma, blastoma, sarcoma, and leukemia. Moreparticular examples of such cancers include squamous cell cancer, lungcancer (including small-cell lung cancer, non-small cell lung cancer,adenocarcinoma of the lung, and squamous carcinoma of the lung), cancerof the peritoneum, hepatocellular cancer, gastric or stomach cancer(including gastrointestinal cancer), pancreatic cancer, glioblastoma,cervical cancer, ovarian cancer, liver cancer, bladder cancer, hepatoma,breast cancer, colon cancer, colorectal cancer, endometrial or uterinecarcinoma, salivary gland carcinoma, kidney or renal cancer, livercancer, prostate cancer, vulval cancer, thyroid cancer, hepaticcarcinoma and various types of head and neck cancer, as well as B-celllymphoma (including low grade/follicular non-Hodgkin's lymphoma (NHL);small lymphocytic (SL) NHL; intermediate grade/follicular NHL;intermediate grade diffuse NHL; high grade immunoblastic NHL; high gradelymphoblastic NHL; high grade small non-cleaved cell NHL; bulky diseaseNHL; mantle cell lymphoma; AIDS-related lymphoma; and Waldenstrom'sMacroglobulinemia); chronic lymphocytic leukemia (CLL); acutelymphoblastic leukemia (ALL); Hairy cell leukemia; chronic myeloblasticleukemia; and post-transplant lymphoproliferative disorder (PTLD), aswell as abnormal vascular proliferation associated with phakomatoses,edema (such as that associated with brain tumors), and Meigs' syndrome.

The term “anti-neoplastic composition” or “anti-cancer composition” or“anti-cancer agent” refers to a composition useful in treating cancercomprising at least one active therapeutic agent, e.g., “anti-canceragent.” Examples of therapeutic agents (anti-cancer agents) include, butare limited to, e.g., chemotherapeutic agents, growth inhibitory agents,cytotoxic agents, agents used in radiation therapy, anti-angiogenesisagents, apoptotic agents, anti-tubulin agents, and other-agents to treatcancer, such as anti-HER-2 antibodies, anti-CD20 antibodies, anepidermal growth factor receptor (EGFR) antagonist (e.g., a tyrosinekinase inhibitor), HER1/EGFR inhibitor (e.g., erlotinib (Tarceva™),platelet derived growth factor inhibitors (e.g., Gleevec™ (ImatinibMesylate)), a COX-2 inhibitor (e.g., celecoxib), interferons, cytokines,antagonists (e.g., neutralizing antibodies) that bind to one or more ofthe following targets ErbB2, ErbB3, ErbB4, PDGFR-beta, BlyS, APRIL, BCMAVEGF, or VEGF receptor(s), TRAIL/Apo2, and other bioactive and organicchemical agents, etc. Combinations thereof are also included in theinvention.

An “angiogenic factor or agent” is a growth factor which stimulates thedevelopment of blood vessels, e.g., promote angiogenesis, endothelialcell growth, stability of blood vessels, and/or vasculogenesis, etc. Forexample, angiogenic factors, include, but are not limited to, e.g., VEGFand members of the VEGF family, PlGF, PDGF family, fibroblast growthfactor family (FGFs), TIE ligands (Angiopoietins), ephrins, Del-1,fibroblast growth factors: acidic (aFGF) and basic (bFGF), Follistatin,Granulocyte colony-stimulating factor (G-CSF), Hepatocyte growth factor(HGF)/scatter factor (SF), Interleukin-8 (IL-8), Leptin, Midkine,Placental growth factor, Platelet-derived endothelial cell growth factor(PD-ECGF), Platelet-derived growth factor, especially PDGF-BB orPDGFR-beta, Pleiotrophin (PTN), Progranulin, Proliferin, Transforminggrowth factor-alpha (TGF-alpha), Transforming growth factor-beta(TGF-beta), Tumor necrosis factor-alpha (TNF-alpha), Vascularendothelial growth factor (VEGF)/vascular permeability factor (VPF),etc. It would also include factors that accelerate wound healing, suchas growth hormone, insulin-like growth factor-I (IGF-I), VIGF, epidermalgrowth factor (EGF), CTGF and members of its family, and TGF-alpha andTGF-beta. See, e.g., Klagsbrun and D'Amore, Annu. Rev. Physiol.,53:217-39 (1991); Streit and Detmar, Oncogene, 22:3172-3179 (2003);Ferrara & Alitalo, Nature Medicine 5(12):1359-1364 (1999); Tonini etal., Oncogene, 22:6549-6556 (2003) (e.g., Table 1 listing knownangiogenic factors); and, Sato Int. J. Clin. Oncol., 8:200-206 (2003).

The term “VEGF” as used herein refers to the 165-amino acid humanvascular endothelial cell growth factor and related 121-, 189-, and206-amino acid human vascular endothelial cell growth factors, asdescribed by Leung et al. Science, 246:1306 (1989), and Houck et al.Mol. Endocrin., 5:1806 (1991), together with the naturally occurringallelic and processed forms thereof. The term “VEGF” also refers toVEGFs from non-human species such as mouse, rat or primate. Sometimesthe VEGF from a specific species are indicated by terms such as hVEGFfor human VEGF, mVEGF for murine VEGF, and etc. The term “VEGF” is alsoused to refer to truncated forms of the polypeptide comprising aminoacids 8 to 109 or 1 to 109 of the 165-amino acid human vascularendothelial cell growth factor. Reference to any such forms of VEGF maybe identified in the present application, e.g., by “VEGF (8-109),” “VEGF(1-109)” or “VEGF₁₆₅.” The amino acid positions for a “truncated” nativeVEGF are numbered as indicated in the native VEGF sequence. For example,amino acid position 17 (methionine) in truncated native VEGF is alsoposition 17 (methionine) in native VEGF. The truncated native VEGF hasbinding affinity for the KDR and Flt-1 receptors comparable to nativeVEGF. According to a preferred embodiment, the VEGF is a human VEGF.

A “VEGF antagonist” refers to a molecule capable of neutralizing,blocking, inhibiting, abrogating, reducing or interfering with VEGFactivities including its binding to VEGF or one or more VEGF receptorsor the nucleic acid encoding them. Preferrably, the VEGF antagonistbinds VEGF or a VEGF receptor. VEGF antagonists include anti-VEGFantibodies and antigen-binding fragments thereof, polypeptides that bindVEGF and VEGF receptors and block ligand-receptor interaction (e.g.,immunoadhesins, peptibodies), anti-VEGF receptor antibodies and VEGFreceptor antagonists such as small molecule inhibitors of the VEGFRtyrosine kinases, aptamers that bind VEGF and nucleic acids thathybridize under stringent conditions to nucleic acid sequences thatencode VEGF or VEGF receptor (e.g., RNAi). According to one preferredembodiment, the VEGF antagonist binds to VEGF and inhibits VEGF-inducedendothelial cell proliferation in vitro. According to one preferredembodiment, the VEGF antagonist binds to VEGF or a VEGF receptor withgreater affinity than a non-VEGF or non-VEGF receptor. According to onepreferred embodiment, the VEG antagonist binds to VEGF or a VEGFreceptor with a Kd of between 1 uM and 1 pM. According to anotherpreferred embodiment, the VEGF antagonist binds to VEGF or a VEGFreceptor between 500 nM and 1 pM.

According a preferred embodiment, the VEGF antagonist is selected fromthe group consisting of a polypeptide such as an antibody, a peptibody,an immunoadhesin, a small molecule or an aptamer. In a preferredembodiment, the antibody is an anti-VEGF antibody such as the AVASTIN®antibody or an anti-VEGF receptor antibody such as an anti-VEGFR2 or ananti-VEGFR3 antibody. Other examples of VEGF antagonists include:VEGF-Trap, Mucagen, PTK787, SU11248, AG-013736, Bay 439006 (sorafenib),ZD-6474, CP632, CP-547632, AZD-2171, CDP-171, SU-14813, CHIR-258,AEE-788, SB786034, BAY579352, CDP-791, EG-3306, GW-786034,RWJ-417975/CT6758 and KRN-633.

An “anti-VEGF antibody” is an antibody that binds to VEGF withsufficient affinity and specificity. Preferably, the anti-VEGF antibodyof the invention can be used as a therapeutic agent in targeting andinterfering with diseases or conditions wherein the VEGF activity isinvolved. An anti-VEGF antibody will usually not bind to other VEGFhomologues such as VEGF-B or VEGF-C, nor other growth factors such asPlGF, PDGF or bFGF. A preferred anti-VEGF antibody is a monoclonalantibody that binds to the same epitope as the monoclonal anti-VEGFantibody A4.6.1 produced by hybridoma ATCC HB 10709. More preferably theanti-VEGF antibody is a recombinant humanized anti-VEGF monoclonalantibody generated according to Presta et al. (1997) Cancer Res.57:4593-4599, including but not limited to the antibody known asbevacizumab (BV; Avastin®). According to another embodiment, anti-VEGFantibodies that can be used include, but are not limited to theantibodies disclosed in WO 2005/012359. According to one embodiment, theanti-VEGF antibody comprises the variable heavy and variable lightregion of any one of the antibodies disclosed in FIGS. 24, 25, 26, 27and 29 of WO 2005/012359 (e.g., G6, G6-23, G6-31, G6-23.1, G6-23.2, B20,B20-4 and B20.4.1). In another preferred embodiment, the anti-VEGFantibody known as ranibizumab is the VEGF antagonist administered forocular disease such as diabetic neuropathy and AMD.

The anti-VEGF antibody “Bevacizumab (BV)”, also known as “rhuMAb VEGF”or “Avastin®”, is a recombinant humanized anti-VEGF monoclonal antibodygenerated according to Presta et al. (1997) Cancer Res. 57:4593-4599. Itcomprises mutated human IgG1 framework regions and antigen-bindingcomplementarity-determining regions from the murine anti-hVEGFmonoclonal antibody A.4.6.1 that blocks binding of human VEGF to itsreceptors. Approximately 93% of the amino acid sequence of Bevacizumab,including most of the framework regions, is derived from human IgG1, andabout 7% of the sequence is derived from the murine antibody A4.6.1.Bevacizumab has a molecular mass of about 149,000 daltons and isglycosylated. Other anti-VEGF antibodies include the antibodiesdescribed in U.S. Pat. No. 6,884,879 and WO 2005/044853.

The anti-VEGF antibody Ranibizumab or the LUCENTIS® antibody or rhuFabV2 is a humanized, affinity-matured anti-human VEGF Fab fragment.Ranibizumab is produced by standard recombinant technology methods inEscherichia coli expression vector and bacterial fermentation.Ranibizumab is not glycosylated and has a molecular mass of ˜48,000daltons. See WO98/45331 and US20030190317.

Dysregulation of angiogenesis can lead to abnormal angiogenesis, i.e.,when excessive or inappropriate growth of new blood vessels (e.g., thelocation, timing or onset of the angiogenesis being undesired from amedical standpoint) in a diseased state or such that it causes adiseased state. Excessive, inappropriate or uncontrolled angiogenesisoccurs when there is new blood vessel growth that contributes to theworsening of the diseased state or causes a diseased state. The newblood vessels can feed the diseased tissues, destroy normal tissues, andin the case of cancer, the new vessels can allow tumor cells to escapeinto the circulation and lodge in other organs (tumor metastases).Disease states involving abnormal angiogenesis include bothnon-neoplastic and neoplastic conditions including, e.g., cancer,especially vascularized solid tumors and metastatic tumors (includingcolon cancer, breast cancer, lung cancer (especially small-cell lungcancer), or prostate cancer), undesired or aberrant hypertrophy,arthritis, rheumatoid arthritis (RA), inflammatory bowel disease or IBD(Crohn's disease and ulcerative colitis), psoriasis, psoriatic plaques,sarcoidosis, atherosclerosis, atherosclerotic plaques, diabetic andother proliferative retinopathies including retinopathy of prematurity,retrolental fibroplasia, neovascular glaucoma, age-related maculardegeneration, diabetic macular edema, corneal neovascularization,corneal graft neovascularization, corneal graft rejection,retinal/choroidal neovascularization, neovascularization of the anteriorsurface of the iris (rubeosis), ocular neovascular disease, vascularrestenosis, arteriovenous malformations (AVM), meningioma, hemangioma,angiofibroma, thyroid hyperplasias (including Grave's disease), chronicinflammation, lung inflammation, acute lung injury/ARDS, sepsis, primarypulmonary hypertension, malignant pulmonary effusions, cerebral edema(e.g., associated with acute stroke/closed head injury/trauma), synovialinflammation, myositis ossificans, hypertropic bone formation,osteoarthritis (OA), refractory ascites, polycystic ovarian disease,endometriosis, 3rd spacing of fluid diseases (pancreatitis, compartmentsyndrome, burns, bowel disease), uterine fibroids, premature labor,chronic inflammation such as IBD, renal allograft rejection,inflammatory bowel disease, nephrotic syndrome, undesired or aberranttissue mass growth (non-cancer), hemophilic joints, hypertrophic scars,inhibition of hair growth, Osler-Weber syndrome, pyogenic granulomaretrolental fibroplasias, scleroderma, trachoma, vascular adhesions,synovitis, dermatitis, preeclampsia, ascites, pericardial effusion (suchas that associated with pericarditis), and pleural effusion.

As used herein, “treatment” refers to clinical intervention in anattempt to alter the natural course of the individual or cell beingtreated, and can be performed either for prophylaxis or during thecourse of clinical pathology. Desirable effects of treatment includepreventing occurrence or recurrence of disease, alleviation of symptoms,diminishment of any direct or indirect pathological consequences of thedisease, preventing metastasis, decreasing the rate of diseaseprogression, amelioration or palliation of the disease state, andremission or improved prognosis. In some embodiments, antibodies of theinvention are used to delay development of a disease or disorder.

An “effective amount” refers to an amount effective, at dosages and forperiods of time necessary, to achieve the desired therapeutic orprophylactic result.

A “therapeutically effective amount” of a substance/molecule of theinvention, agonist or antagonist may vary according to factors such asthe disease state, age, sex, and weight of the individual, and theability of the substance/molecule, agonist or antagonist to elicit adesired response in the individual. A therapeutically effective amountis also one in which any toxic or detrimental effects of thesubstance/molecule, agonist or antagonist are outweighed by thetherapeutically beneficial effects. The term “therapeutically effectiveamount” refers to an amount of an antibody, polypeptide or antagonist ofthis invention effective to “treat” a disease or disorder in a mammal(aka patient). In the case of cancer, the therapeutically effectiveamount of the drug can reduce the number of cancer cells; reduce thetumor size or weight; inhibit (i.e., slow to some extent and preferablystop) cancer cell infiltration into peripheral organs; inhibit (i.e.,slow to some extent and preferably stop) tumor metastasis; inhibit, tosome extent, tumor growth; and/or relieve to some extent one or more ofthe symptoms associated with the cancer. To the extent the drug canprevent growth and/or kill existing cancer cells, it can be cytostaticand/or cytotoxic. In one embodiment, the therapeutically effectiveamount is a growth inhibitory amount. In another embodiment, thetherapeutically effective amount is an amount that extends the survivalof a patient. In another embodiment, the therapeutically effectiveamount is an amount that improves progression free survival of apatient.

A “prophylactically effective amount” refers to an amount effective, atdosages and for periods of time necessary, to achieve the desiredprophylactic result. Typically but not necessarily, since a prophylacticdose is used in subjects prior to or at an earlier stage of disease, theprophylactically effective amount is less than the therapeuticallyeffective amount.

The term “cytotoxic agent” as used herein refers to a substance thatinhibits or prevents the function of cells and/or causes destruction ofcells. The term is intended to include radioactive isotopes (e.g.,At²¹¹, I¹³¹, I¹²⁵, Y⁹⁰, Re¹⁸⁶, Re¹⁸⁸, Sm¹⁵³, Bi²¹², P³² and radioactiveisotopes of Lu), chemotherapeutic agents e.g. methotrexate, adriamicin,vinca alkaloids (vincristine, vinblastine, etoposide), doxorubicin,melphalan, mitomycin C, chlorambucil, daunorubicin or otherintercalating agents, enzymes and fragments thereof such as nucleolyticenzymes, antibiotics, and toxins such as small molecule toxins orenzymatically active toxins of bacterial, fungal, plant or animalorigin, including fragments and/or variants thereof, and the variousantitumor or anticancer agents disclosed below. Other cytotoxic agentsare described below. A tumoricidal agent causes destruction of tumorcells.

A “chemotherapeutic agent” is a chemical compound useful in thetreatment of cancer. Examples of chemotherapeutic agents includealkylating agents such as thiotepa and CYTOXAN® cyclosphosphamide; alkylsulfonates such as busulfan, improsulfan and piposulfan; aziridines suchas benzodopa, carboquone, meturedopa, and uredopa; ethylenimines andmethylamelamines including altretamine, triethylenemelamine,trietylenephosphoramide, triethiylenethiophosphoramide andtrimethylolomelamine; acetogenins (especially bullatacin andbullatacinone); delta-9-tetrahydrocannabinol (dronabinol, MARINOL®);beta-lapachone; lapachol; colchicines; betulinic acid; a camptothecin(including the synthetic analogue topotecan (HYCAMTIN®), CPT-11(irinotecan, CAMPTOSAR®), acetylcamptothecin, scopolectin, and9-aminocamptothecin); bryostatin; callystatin; CC-1065 (including itsadozelesin, carzelesin and bizelesin synthetic analogues);podophyllotoxin; podophyllinic acid; teniposide; cryptophycins(particularly cryptophycin 1 and cryptophycin 8); dolastatin;duocarmycin (including the synthetic analogues, KW-2189 and CB1-TM1);eleutherobin; pancratistatin; a sarcodictyin; spongistatin; nitrogenmustards such as chlorambucil, chlornaphazine, cholophosphamide,estramustine, ifosfamide, mechlorethamine, mechlorethamine oxidehydrochloride, melphalan, novembichin, phenesterine, prednimustine,trofosfamide, uracil mustard; nitrosureas such as carmustine,chlorozotocin, fotemustine, lomustine, nimustine, and ranimnustine;antibiotics such as the enediyne antibiotics (e.g., calicheamicin,especially calicheamicin gamma1I and calicheamicin omegaI1 (see, e.g.,Agnew, Chem Intl. Ed. Engl., 33: 183-186 (1994)); dynemicin, includingdynemicin A; an esperamicin; as well as neocarzinostatin chromophore andrelated chromoprotein enediyne antiobiotic chromophores),aclacinomysins, actinomycin, authramycin, azaserine, bleomycins,cactinomycin, carabicin, caminomycin, carzinophilin, chromomycinis,dactinomycin, daunorubicin, detorubicin, 6-diazo-5-oxo-L-norleucine,ADRIAMYCIN® doxorubicin (including morpholino-doxorubicin,cyanomorpholino-doxorubicin, 2-pyrrolino-doxorubicin anddeoxydoxorubicin), epirubicin, esorubicin, idarubicin, marcellomycin,mitomycins such as mitomycin C, mycophenolic acid, nogalamycin,olivomycins, peplomycin, potfiromycin, puromycin, quelamycin,rodorubicin, streptonigrin, streptozocin, tubercidin, ubenimex,zinostatin, zorubicin; anti-metabolites such as methotrexate and5-fluorouracil (5-FU); folic acid analogues such as denopterin,methotrexate, pteropterin, trimetrexate; purine analogs such asfludarabine, 6-mercaptopurine, thiamiprine, thioguanine; pyrimidineanalogs such as ancitabine, azacitidine, 6-azauridine, carmofur,cytarabine, dideoxyuridine, doxifluridine, enocitabine, floxuridine;androgens such as calusterone, dromostanolone propionate, epitiostanol,mepitiostane, testolactone; anti-adrenals such as aminoglutethimide,mitotane, trilostane; folic acid replenisher such as frolinic acid;aceglatone; aldophosphamide glycoside; aminolevulinic acid; eniluracil;amsacrine; bestrabucil; bisantrene; edatraxate; defofamine; demecolcine;diaziquone; elfornithine; elliptinium acetate; an epothilone; etoglucid;gallium nitrate; hydroxyurea; lentinan; lonidainine; maytansinoids suchas maytansine and ansamitocins; mitoguazone; mitoxantrone; mopidanmol;nitraerine; pentostatin; phenamet; pirarubicin; losoxantrone;2-ethylhydrazide; procarbazine; PSK® polysaccharide complex (JHS NaturalProducts, Eugene, Oreg.); razoxane; rhizoxin; sizofuran; spirogermanium;tenuazonic acid; triaziquone; 2,2′,2″-trichlorotriethylamine;trichothecenes (especially T-2 toxin, verracurin A, roridin A andanguidine); urethan; vindesine (ELDISINE®, FILDESIN®); dacarbazine;mannomustine; mitobronitol; mitolactol; pipobroman; gacytosine;arabinoside (“Ara-C”); thiotepa; taxoids, e.g., TAXOL® paclitaxel(Bristol-Myers Squibb Oncology, Princeton, N.J.), ABRAXANE™Cremophor-free, albumin-engineered nanoparticle formulation ofpaclitaxel (American Pharmaceutical Partners, Schaumberg, Ill.), andTAXOTERE® doxetaxel (Rhône-Poulenc Rorer, Antony, France); chloranbucil;gemcitabine (GEMZAR®); 6-thioguanine; mercaptopurine; methotrexate;platinum analogs such as cisplatin and carboplatin; vinblastine(VELBAN®); platinum; etoposide (VP-16); ifosfamide; mitoxantrone;vincristine (ONCOVIN®); oxaliplatin; leucovovin; vinorelbine(NAVELBINE®); novantrone; edatrexate; daunomycin; aminopterin;ibandronate; topoisomerase inhibitor RFS 2000; difluoromethylornithine(DMFO); retinoids such as retinoic acid; capecitabine (XELODA®);pharmaceutically acceptable salts, acids or derivatives of any of theabove; as well as combinations of two or more of the above such as CHOP,an abbreviation for a combined therapy of cyclophosphamide, doxorubicin,vincristine, and prednisolone, and FOLFOX, an abbreviation for atreatment regimen with oxaliplatin (ELOXATIN™) combined with 5-FU andleucovovin. Additional chemotherapeutic agents include the cytotoxicagents useful as antibody drug conjugates, such as maytansinoids (DM1,for example) and the auristatins MMAE and MMAF, for example.

“Chemotherapeutic agents” also include “anti-hormonal agents” that actto regulate, reduce, block, or inhibit the effects of hormones that canpromote the growth of cancer, and are often in the form of systemic, orwhole-body treatment. They may be hormones themselves. Examples includeanti-estrogens and selective estrogen receptor modulators (SERMs),including, for example, tamoxifen (including NOLVADEX® tamoxifen),EVISTA® raloxifene, droloxifene, 4-hydroxytamoxifen, trioxifene,keoxifene, LY117018, onapristone, and FARESTON® toremifene;anti-progesterones; estrogen receptor down-regulators (ERDs); agentsthat function to suppress or shut down the ovaries, for example,leutinizing hormone-releasing hormone (LHRH) agonists such as LUPRON®and ELIGARD® leuprolide acetate, goserelin acetate, buserelin acetateand tripterelin; other anti-androgens such as flutamide, nilutamide andbicalutamide; and aromatase inhibitors that inhibit the enzymearomatase, which regulates estrogen production in the adrenal glands,such as, for example, 4(5)-imidazoles, aminoglutethimide, MEGASE®megestrol acetate, AROMASIN® exemestane, formestanie, fadrozole,RIVISOR® vorozole, FEMARA® letrozole, and ARIMIDEX® anastrozole. Inaddition, such definition of chemotherapeutic agents includesbisphosphonates such as clodronate (for example, BONEFOS® or OSTAC®),DIDROCAL® etidronate, NE-58095, ZOMETA® zoledronic acid/zoledronate,FOSAMAX® alendronate, AREDIA® pamidronate, SKELID® tiludronate, orACTONEL® risedronate; as well as troxacitabine (a 1,3-dioxolanenucleoside cytosine analog); antisense oligonucleotides, particularlythose that inhibit expression of genes in signaling pathways implicatedin abherant cell proliferation, such as, for example, PKC-alpha, Raf,H-Ras, and epidermal growth factor receptor (EGF-R); vaccines such asTHERATOPE® vaccine and gene therapy vaccines, for example, ALLOVECTIN®vaccine, LEUVECTIN® vaccine, and VAXID® vaccine; LURTOTECAN®topoisomerase 1 inhibitor; ABARELIX® rmRH; lapatinib ditosylate (anErbB-2 and EGFR dual tyrosine kinase small-molecule inhibitor also knownas GW572016); and pharmaceutically acceptable salts, acids orderivatives of any of the above.

A “growth inhibitory agent” when used herein refers to a compound orcomposition which inhibits growth and/or proliferation of a cell (e.g.,a cell expressing Robo4) either in vitro or in vivo. Thus, the growthinhibitory agent may be one which significantly reduces the percentageof Robo4-expressing cells in S phase. Examples of growth inhibitoryagents include agents that block cell cycle progression (at a placeother than S phase), such as agents that induce G1 arrest and M-phasearrest. Classical M-phase blockers include the vincas (vincristine andvinblastine), taxanes, and topoisomerase II inhibitors such asdoxorubicin, epirubicin, daunorubicin, etoposide, and bleomycin. Thoseagents that arrest G1 also spill over into S-phase arrest, for example,DNA alkylating agents such as tamoxifen, prednisone, dacarbazine,mechlorethamine, cisplatin, methotrexate, 5-fluorouracil, and ara-C.Further information can be found in The Molecular Basis of Cancer,Mendelsohn and Israel, eds., Chapter 1, entitled “Cell cycle regulation,oncogenes, and antineoplastic drugs” by Murakami et al. (WB Saunders:Philadelphia, 1995), especially p. 13. The taxanes (paclitaxel anddocetaxel) are anticancer drugs both derived from the yew tree.Docetaxel (TAXOTERE®, Rhone-Poulenc Rorer), derived from the Europeanyew, is a semisynthetic analogue of paclitaxel (TAXOL®, Bristol-MyersSquibb). Paclitaxel and docetaxel promote the assembly of microtubulesfrom tubulin dimers and stabilize microtubules by preventingdepolymerization, which results in the inhibition of mitosis in cells.

“Doxorubicin” is an anthracycline antibiotic. The full chemical name ofdoxorubicin is(8S-cis)-10-[(3-amino-2,3,6-trideoxy-α-L-lyxo-hexapyranosyl)oxy]-7,8,9,10-tetrahydro-6,8,11-trihydroxy-8-(hydroxyacetyl)-1-methoxy-5,12-naphthacenedione.

III. Anti-Robo4 Antibodies

In one aspect, the invention provides antibodies that bind to Robo4. Inone embodiment, an anti-Robo4 antibody is a monoclonal antibody. In oneembodiment, an anti-Robo4 antibody is an antibody fragment, e.g., a Fab,Fab′-SH, Fv, scFv, or (Fab′)₂ fragment. In one embodiment, an anti-Robo4antibody is a chimeric, humanized, or human antibody. In one embodiment,an anti-Robo4 antibody is purified.

In another aspect of the invention, polynucleotides encoding anti-Robo4antibodies are provided. In certain embodiments, vectors comprisingpolynucleotides encoding anti-Robo4 antibodies are provided. In certainembodiments, host cells comprising such vectors are provided. In anotheraspect of the invention, compositions comprising anti-Robo4 antibodiesor polynucleotides encoding anti-Robo4 antibodies are provided. Incertain embodiments, a composition is a pharmaceutical formulation forthe treatment of diseases and disorders including, e.g., cancer,atherosclerosis, retrolental fibroplasia, hemangiomas, chronicinflammation, intraocular neovascular diseases, proliferativeretinopathies, diabetic retinopathy, age-related macular degeneration(AMD), neovascular glaucoma, immune rejection of transplanted cornealtissue and other tissues, rheumatoid arthritis, psoriasis, andcombinations thereof.

Exemplary monoclonal antibodies derived from a phage library areprovided herein and described in the Examples below. Those antibodiesare designated YW71.6, YW71.1, YW71.22, YW71.89, YW79.1, YW79.8, andYW79.11. Those antibodies were affinity matured to generateYW71.22.S1.2, YW71.22S1.8, YW71.22S1.16, YW71.22S1.23, YW71.22S1.24,YW71.22S1.27, YW71.22S1.31, YW71.22S1.38, YW71.22S1.77 YW71.22.S2.21,YW71.22.S2.79, YW71.22.H1.2, YW71.22.H1.9, YW71.22.H1.46, YW71.22.H1.77,YW71.22.H1.91, and YW71.22.H2.31. The sequences of the heavy and lightchain variable domains of the antibodies are set forth in FIGS. 1 and 2.

An antibody of the invention can comprise any suitable human or humanconsensus light chain framework sequences, provided the antibodyexhibits the desired biological characteristics (e.g., a desired bindingaffinity).

In one embodiment, human consensus frameworks herein are from, orderived from, VH subgroup III (see FIGS. 4A and 4B) and/or VL kappasubgroup I (see FIGS. 3A and 3B) consensus framework sequences.

Thus, the VH acceptor human framework may comprise one, two, three orall four of the following framework sequences:

FR1 comprising EVQLVESGGGLVQPGGSLRLSCAAS, (SEQ ID NO: 13) FR2 comprisingWVRQAPGKGLEWV, (SEQ ID NO: 14) FR3 comprising FR3 comprisesRFTISADTSKNTAYLQMNSLRAEDTAVYYC, (SEQ ID NO: 15) FR4 comprising WGQGTLVTVSS. (SEQ ID NO: 16)

In other embodiments, the VH consensus frameworks include:

human VH subgroup I consensus frameworks 1-4 minus Kabat CDRs (SEQ IDNOS:111, 112, 113, 16);human VH subgroup I consensus frameworks 1-4 minus extendedhypervariable regions (SEQ ID NOS:114, 115, 113, 16 or SEQ ID NOS:114,115, 116, 16 or SEQ ID NOS:114, 115, 117, 16);human VH subgroup II consensus frameworks 1-4 minus Kabat CDRs (SEQ IDNOS: 118, 119, 120, 16);human VH subgroup II consensus frameworks 1-4 minus extendedhypervariable regions (SEQ ID NOS:121, 122, 120, 16 or SEQ ID NOS:121,122, 123, 16 or SEQ ID NOS:121, 122, 124, 16);human VH subgroup III consensus frameworks 1-4 minus Kabat CDRs (SEQ IDNO:125, 126, 127, 16);human VH subgroup III consensus frameworks 1-4 minus extendedhypervariable regions (SEQ ID NOS:128, 129, 127, 16 or SEQ ID NOS:128,129, 130, 16 or SEQ ID NOS:128, 129, 131, 16);human VH acceptor 1 frameworks 1-4 minus Kabat CDRs (SEQ ID NOS:132,126, 133, 16);human VH acceptor 1 frameworks 1-4 minus extended hypervariable regions(SEQ ID NOS:128, 129, 133, 16 or SEQ ID NOS:128, 129, 134, 16);human VH acceptor 2 frameworks 1-4 minus Kabat CDRs (SEQ ID NO:132, 126,135, 16); orhuman VH acceptor 2 frameworks 1-4 minus extended hypervariable regions(SEQ ID NOS:128, 126, 135, 16 or SEQ ID NOS:128, 126, 136, 16 or SEQ IDNOS:128, 126, 137, 16).

In one embodiment, the VH acceptor human framework region 4 (H-FR4)comprises WGQGTLVTVSS (SEQ ID NO:45).

The VL acceptor human framework may comprise one, two, three or four ofthe following framework sequences:

FR1 comprising DIQMTQSPSSLSASVGDRVTITC, (SEQ ID NO: 9) FR2 comprisingWYQQKPGKAPKLLIY, (SEQ ID NO: 10) FR3 comprisingGVPSRFSGSGSGTDFTLTISSLQPEDFATYYC, (SEQ ID NO: 11) FR4 comprisingFGQGTKVEIKR (SEQ ID NO: 173) or FGQGTKMEIKR. (SEQ ID NO: 139)In other embodiment, the VL consensus frameworks include:human VL kappa subgroup I consensus frameworks 1-4 (SEQ ID NOS:9, 10,99, 100);human VL kappa subgroup I consensus frameworks 1-4 (SEQ ID NOS:9, 101,99, 100);human VL kappa subgroup II consensus frameworks 1-4 (SEQ ID NOS:102,103, 104, 100);human VL kappa subgroup III consensus frameworks 1-4 (SEQ ID NOS:105,106, 107, 100); orhuman VL kappa subgroup IV consensus frameworks 1-4 (SEQ ID NOS:108,109, 110, 100)

While the acceptor may be identical in sequence to the human frameworksequence selected, whether that be from a human immunoglobulin or ahuman consensus framework, the present invention contemplates that theacceptor sequence may comprise pre-existing amino acid substitutionsrelative to the human immunoglobulin sequence or human consensusframework sequence. These pre-existing substitutions are preferablyminimal; usually four, three, two or one amino acid differences onlyrelative to the human immunoglobulin sequence or consensus frameworksequence.

Hypervariable region residues of the non-human antibody are incorporatedinto the VL and/or VH acceptor human frameworks. For example, one mayincorporate residues corresponding to the Kabat CDR residues, theChothia hypervariable loop residues, the Abm residues, and/or contactresidues. Optionally, the extended hypervariable region residues asfollows are incorporated: 24-34 (L1), 50-56 (L2) and 89-97 (L3), 26-35(H1), 50-65 or 49-65 (H2) and 93-102, 94-102, or 95-102 (H3).

While “incorporation” of hypervariable region residues is discussedherein, it will be appreciated that this can be achieved in variousways, for example, nucleic acid encoding the desired amino acid sequencecan be generated by mutating nucleic acid encoding the mouse variabledomain sequence so that the framework residues thereof are changed toacceptor human framework residues, or by mutating nucleic acid encodingthe human variable domain sequence so that the hypervariable domainresidues are changed to non-human residues, or by synthesizing nucleicacid encoding the desired sequence, etc.

In the examples herein, hypervariable region-grafted variants weregenerated by Kunkel mutagenesis of nucleic acid encoding the humanacceptor sequences, using a separate oligonucleotide for eachhypervariable region. Kunkel et al., Methods Enzymol. 154:367-382(1987). Appropriate changes can be introduced within the frameworkand/or hypervariable region, using routine techniques, to correct andre-establish proper hypervariable region-antigen interactions.

A. Antibody Fragments

The present invention encompasses antibody fragments. Antibody fragmentsmay be generated by traditional means, such as enzymatic digestion, orby recombinant techniques. In certain circumstances there are advantagesof using antibody fragments, rather than whole antibodies. The smallersize of the fragments allows for rapid clearance, and may lead toimproved access to solid tumors. For a review of certain antibodyfragments, see Hudson et al. (2003) Nat. Med. 9:129-134.

Various techniques have been developed for the production of antibodyfragments. Traditionally, these fragments were derived via proteolyticdigestion of intact antibodies (see, e.g., Morimoto et al., Journal ofBiochemical and Biophysical Methods 24:107-117 (1992); and Brennan etal., Science, 229:81 (1985)). However, these fragments can now beproduced directly by recombinant host cells. Fab, Fv and ScFv antibodyfragments can all be expressed in and secreted from E. coli, thusallowing the facile production of large amounts of these fragments.Antibody fragments can be isolated from the antibody phage librariesdiscussed above. Alternatively, Fab′-SH fragments can be directlyrecovered from E. coli and chemically coupled to form F(ab′)₂ fragments(Carter et al., Bio/Technology 10: 163-167 (1992)). According to anotherapproach, F(ab′)₂ fragments can be isolated directly from recombinanthost cell culture. Fab and F(ab′)₂ fragment with increased in vivohalf-life comprising salvage receptor binding epitope residues aredescribed in U.S. Pat. No. 5,869,046. Other techniques for theproduction of antibody fragments will be apparent to the skilledpractitioner. In certain embodiments, an antibody is a single chain Fvfragment (scFv). See WO 93/16185; U.S. Pat. Nos. 5,571,894; and5,587,458. Fv and scFv are the only species with intact combining sitesthat are devoid of constant regions; thus, they may be suitable forreduced nonspecific binding during in vivo use. scFv fusion proteins maybe constructed to yield fusion of an effector protein at either theamino or the carboxy terminus of an scFv. See Antibody Engineering, ed.Borrebaeck, supra. The antibody fragment may also be a “linearantibody”, e.g., as described in U.S. Pat. No. 5,641,870, for example.Such linear antibodies may be monospecific or bispecific.

B. Humanized Antibodies

The invention encompasses humanized antibodies. Various methods forhumanizing non-human antibodies are known in the art. For example, ahumanized antibody can have one or more amino acid residues introducedinto it from a source which is non-human. These non-human amino acidresidues are often referred to as “import” residues, which are typicallytaken from an “import” variable domain. Humanization can be essentiallyperformed following the method of Winter and co-workers (Jones et al.(1986) Nature 321:522-525; Riechmann et al. (1988) Nature 332:323-327;Verhoeyen et al. (1988) Science 239:1534-1536), by substitutinghypervariable region sequences for the corresponding sequences of ahuman antibody. Accordingly, such “humanized” antibodies are chimericantibodies (U.S. Pat. No. 4,816,567) wherein substantially less than anintact human variable domain has been substituted by the correspondingsequence from a non-human species. In practice, humanized antibodies aretypically human antibodies in which some hypervariable region residuesand possibly some FR residues are substituted by residues from analogoussites in rodent antibodies.

The choice of human variable domains, both light and heavy, to be usedin making the humanized antibodies can be important to reduceantigenicity. According to the so-called “best-fit” method, the sequenceof the variable domain of a rodent antibody is screened against theentire library of known human variable-domain sequences. The humansequence which is closest to that of the rodent is then accepted as thehuman framework for the humanized antibody. See, e.g., Sims et al.(1993) J. Immunol. 151:2296; Chothia et al. (1987) J. Mol. Biol.196:901. Another method uses a particular framework derived from theconsensus sequence of all human antibodies of a particular subgroup oflight or heavy chains. The same framework may be used for severaldifferent humanized antibodies. See, e.g., Carter et al (1992) PNAS USA,89:4285; Presta et al. (1993) J. Immunol., 151:2623.

It is further generally desirable that antibodies be humanized withretention of high affinity for the antigen and other favorablebiological properties. To achieve this goal, according to one method,humanized antibodies are prepared by a process of analysis of theparental sequences and various conceptual humanized products usingthree-dimensional models of the parental and humanized sequences.Three-dimensional immunoglobulin models are commonly available and arefamiliar to those skilled in the art. Computer programs are availablewhich illustrate and display probable three-dimensional conformationalstructures of selected candidate immunoglobulin sequences. Inspection ofthese displays permits analysis of the likely role of the residues inthe functioning of the candidate immunoglobulin sequence, i.e., theanalysis of residues that influence the ability of the candidateimmunoglobulin to bind its antigen. In this way, FR residues can beselected and combined from the recipient and import sequences so thatthe desired antibody characteristic, such as increased affinity for thetarget antigen(s), is achieved. In general, the hypervariable regionresidues are directly and most substantially involved in influencingantigen binding.

In some embodiments, the invention provides antibodies that arehumanized such that HAMA response is reduced or eliminated. Reduction orelimination of a HAMA response is a significant aspect of clinicaldevelopment of suitable therapeutic agents. See, e.g., Khaxzaeli et al.,J. Natl. Cancer Inst. (1988), 80:937; Jaffers et al., Transplantation(1986), 41:572; Shawler et al., J. Immunol. (1985), 135:1530; Sears etal., J. Biol. Response Mod. (1984), 3:138; Miller et al., Blood (1983),62:988; Hakimi et al., J. Immunol. (1991), 147:1352; Reichmann et al.,Nature (1988), 332:323; Junghans et al., Cancer Res. (1990), 50:1495.Variants of these antibodies can further be obtained using routinemethods known in the art, some of which are further described below.

For example, an amino acid sequence from an antibody as described hereincan serve as a starting (parent) sequence for diversification of theframework and/or hypervariable sequence(s). A selected frameworksequence to which a starting hypervariable sequence is linked isreferred to herein as an acceptor human framework. While the acceptorhuman frameworks may be from, or derived from, a human immunoglobulin(the VL and/or VH regions thereof), preferably the acceptor humanframeworks are from, or derived from, a human consensus frameworksequence as such frameworks have been demonstrated to have minimal, orno, immunogenicity in human patients.

Where the acceptor is derived from a human immunoglobulin, one mayoptionally select a human framework sequence that is selected based onits homology to the donor framework sequence by aligning the donorframework sequence with various human framework sequences in acollection of human framework sequences, and select the most homologousframework sequence as the acceptor.

C. Human Antibodies

Human antibodies of the invention can be constructed by combining Fvclone variable domain sequence(s) selected from human-derived phagedisplay libraries with known human constant domain sequences(s) asdescribed above. Alternatively, human monoclonal antibodies of theinvention can be made by the hybridoma method. Human myeloma andmouse-human heteromyeloma cell lines for the production of humanmonoclonal antibodies have been described, for example, by Kozbor J.Immunol., 133: 3001 (1984); Brodeur et al., Monoclonal AntibodyProduction Techniques and Applications, pp. 51-63 (Marcel Dekker, Inc.,New York, 1987); and Boerner et al., J. Immunol., 147: 86 (1991).

It is now possible to produce transgenic animals (e.g. mice) that arecapable, upon immunization, of producing a full repertoire of humanantibodies in the absence of endogenous immunoglobulin production. Forexample, it has been described that the homozygous deletion of theantibody heavy-chain joining region (JH) gene in chimeric and germ-linemutant mice results in complete inhibition of endogenous antibodyproduction. Transfer of the human germ-line immunoglobulin gene array insuch germ-line mutant mice will result in the production of humanantibodies upon antigen challenge. See, e.g., Jakobovits et al., PNASUSA, 90: 2551 (1993); Jakobovits et al., Nature, 362: 255 (1993);Bruggermann et al., Year in Immunol., 7: 33 (1993).

Gene shuffling can also be used to derive human antibodies fromnon-human, e.g. rodent, antibodies, where the human antibody has similaraffinities and specificities to the starting non-human antibody.According to this method, which is also called “epitope imprinting”,either the heavy or light chain variable region of a non-human antibodyfragment obtained by phage display techniques as described herein isreplaced with a repertoire of human V domain genes, creating apopulation of non-human chain/human chain scFv or Fab chimeras.Selection with antigen results in isolation of a non-human chain/humanchain chimeric scFv or Fab wherein the human chain restores the antigenbinding site destroyed upon removal of the corresponding non-human chainin the primary phage display clone, i.e. the epitope governs (imprints)the choice of the human chain partner. When the process is repeated inorder to replace the remaining non-human chain, a human antibody isobtained (see PCT WO 93/06213 published Apr. 1, 1993). Unliketraditional humanization of non-human antibodies by CDR grafting, thistechnique provides completely human antibodies, which have no FR or CDRresidues of non-human origin.

D. Antibody Variants

In some embodiments, amino acid sequence modification(s) of theantibodies described herein are contemplated. For example, it may bedesirable to improve the binding affinity and/or other biologicalproperties of the antibody. Amino acid sequence variants of the antibodymay be prepared by introducing appropriate changes into the nucleotidesequence encoding the antibody, or by peptide synthesis. Suchmodifications include, for example, deletions from, and/or insertionsinto and/or substitutions of, residues within the amino acid sequencesof the antibody. Any combination of deletion, insertion, andsubstitution can be made to arrive at the final construct, provided thatthe final construct possesses the desired characteristics. The aminoacid alterations may be introduced in the subject antibody amino acidsequence at the time that sequence is made.

A useful method for identification of certain residues or regions of theantibody that are preferred locations for mutagenesis is called “alaninescanning mutagenesis” as described by Cunningham and Wells (1989)Science, 244:1081-1085. Here, a residue or group of target residues areidentified (e.g., charged residues such as arg, asp, his, lys, and glu)and replaced by a neutral or negatively charged amino acid (e.g.,alanine or polyalanine) to affect the interaction of the amino acidswith antigen. Those amino acid locations demonstrating functionalsensitivity to the substitutions then are refined by introducing furtheror other variants at, or for, the sites of substitution. Thus, while thesite for introducing an amino acid sequence variation is predetermined,the nature of the mutation per se need not be predetermined. Forexample, to analyze the performance of a mutation at a given site, alascanning or random mutagenesis is conducted at the target codon orregion and the expressed immunoglobulins are screened for the desiredactivity.

Amino acid sequence insertions include amino- and/or carboxyl-terminalfusions ranging in length from one residue to polypeptides containing ahundred or more residues, as well as intrasequence insertions of singleor multiple amino acid residues. Examples of terminal insertions includean antibody with an N-terminal methionyl residue. Other insertionalvariants of the antibody molecule include the fusion to the N- orC-terminus of the antibody to an enzyme (e.g. for ADEPT) or apolypeptide which increases the serum half-life of the antibody.

In certain embodiments, an antibody of the invention is altered toincrease or decrease the extent to which the antibody is glycosylated.Glycosylation of polypeptides is typically either N-linked or O-linked.N-linked refers to the attachment of a carbohydrate moiety to the sidechain of an asparagine residue. The tripeptide sequencesasparagine-X-serine and asparagine-X-threonine, where X is any aminoacid except proline, are the recognition sequences for enzymaticattachment of the carbohydrate moiety to the asparagine side chain.Thus, the presence of either of these tripeptide sequences in apolypeptide creates a potential glycosylation site. O-linkedglycosylation refers to the attachment of one of the sugarsN-aceylgalactosamine, galactose, or xylose to a hydroxyamino acid, mostcommonly serine or threonine, although 5-hydroxyproline or5-hydroxylysine may also be used.

Addition or deletion of glycosylation sites to the antibody isconveniently accomplished by altering the amino acid sequence such thatone or more of the above-described tripeptide sequences (for N-linkedglycosylation sites) is created or removed. The alteration may also bemade by the addition, deletion, or substitution of one or more serine orthreonine residues to the sequence of the original antibody (forO-linked glycosylation sites).

Where the antibody comprises an Fc region, the carbohydrate attachedthereto may be altered. Native antibodies produced by mammalian cellstypically comprise a branched, biantennary oligosaccharide that isgenerally attached by an N-linkage to Asn297 of the CH2 domain of the Fcregion. See, e.g., Wright et al. (1997) TIBTECH 15:26-32. Theoligosaccharide may include various carbohydrates, e.g., mannose,N-acetyl glucosamine (GlcNAc), galactose, and sialic acid, as well as afucose attached to a GlcNAc in the “stem” of the biantennaryoligosaccharide structure. In some embodiments, modifications of theoligosaccharide in an antibody of the invention may be made in order tocreate antibody variants with certain improved properties.

For example, antibody variants are provided having a carbohydratestructure that lacks fucose attached (directly or indirectly) to an Fcregion. Such variants may have improved ADCC function. See, e.g., USPatent Publication Nos. US 2003/0157108 (Presta, L.); US 2004/0093621(Kyowa Hakko Kogyo Co., Ltd). Examples of publications related to“defucosylated” or “fucose-deficient” antibody variants include: US2003/0157108; WO 2000/61739; WO 2001/29246; US 2003/0115614; US2002/0164328; US 2004/0093621; US 2004/0132140; US 2004/0110704; US2004/0110282; US 2004/0109865; WO 2003/085119; WO 2003/084570; WO2005/035586; WO 2005/035778; WO2005/053742; WO2002/031140; Okazaki etal. J. Mol. Biol. 336:1239-1249 (2004); Yamane-Ohnuki et al. Biotech.Bioeng. 87: 614 (2004). Examples of cell lines capable of producingdefucosylated antibodies include Lec 13 CHO cells deficient in proteinfucosylation (Ripka et al. Arch. Biochem. Biophys. 249:533-545 (1986);US Pat Appl No US 2003/0157108 A1, Presta, L; and WO 2004/056312 A1,Adams et al., especially at Example 11), and knockout cell lines, suchas alpha-1,6-fucosyltransferase gene, FUT8, knockout CHO cells (see,e.g., Yamane-Ohnuki et al. Biotech. Bioeng. 87: 614 (2004); Kanda, Y. etal., Biotechnol. Bioeng., 94(4):680-688 (2006); and WO2003/085107).

Antibodies variants are further provided with bisected oligosaccharides,e.g., in which a biantennary oligosaccharide attached to the Fc regionof the antibody is bisected by GlcNAc. Such antibody variants may havereduced fucosylation and/or improved ADCC function. Examples of suchantibody variants are described, e.g., in WO 2003/011878 (Jean-Mairet etal.); U.S. Pat. No. 6,602,684 (Umana et al.); and US 2005/0123546 (Umanaet al.). Antibody variants with at least one galactose residue in theoligosaccharide attached to the Fc region are also provided. Suchantibody variants may have improved CDC function. Such antibody variantsare described, e.g., in WO 1997/30087 (Patel et al.); WO 1998/58964(Raju, S.); and WO 1999/22764 (Raju, S.).

In certain embodiments, an antibody variant comprises an Fc region withone or more amino acid substitutions which further improve ADCC, forexample, substitutions at positions 298, 333, and/or 334 of the Fcregion (Eu numbering of residues). Such substitutions may occur incombination with any of the variations described above.

In certain embodiments, the invention contemplates an antibody variantthat possesses some but not all effector functions, which make it adesirable candidate for many applications in which the half life of theantibody in vivo is important yet certain effector functions (such ascomplement and ADCC) are unnecessary or deleterious. In certainembodiments, the Fc activities of the antibody are measured to ensurethat only the desired properties are maintained. In vitro and/or in vivocytotoxicity assays can be conducted to confirm the reduction/depletionof CDC and/or ADCC activities. For example, Fc receptor (FcR) bindingassays can be conducted to ensure that the antibody lacks FcγR binding(hence likely lacking ADCC activity), but retains FcRn binding ability.The primary cells for mediating ADCC, NK cells, express FcγRIII only,whereas monocytes express FcγRI, FcγRII and FcγRIII. FcR expression onhematopoietic cells is summarized in Table 3 on page 464 of Ravetch andKinet, Annu. Rev. Immunol. 9:457-92 (1991). Non-limiting examples of invitro assays to assess ADCC activity of a molecule of interest isdescribed in U.S. Pat. No. 5,500,362 (see, e.g. Hellstrom, I., et al.PNAS USA 83:7059-7063 (1986)) and Hellstrom, I et al., PNAS USA82:1499-1502 (1985); U.S. Pat. No. 5,821,337 (see Bruggemann, M. et al.,J. Exp. Med. 166:1351-1361 (1987)). Alternatively, non-radioactiveassays methods may be employed (see, for example, ACTI™ non-radioactivecytotoxicity assay for flow cytometry (CellTechnology, Inc. MountainView, Calif.; and CytoTox 96® non-radioactive cytotoxicity assay(Promega, Madison, Wis.). Useful effector cells for such assays includeperipheral blood mononuclear cells (PBMC) and Natural Killer (NK) cells.Alternatively, or additionally, ADCC activity of the molecule ofinterest may be assessed in vivo, e.g., in a animal model such as thatdisclosed in Clynes et al. PNAS USA 95:652-656 (1998). C1q bindingassays may also be carried out to confirm that the antibody is unable tobind C1q and hence lacks CDC activity. To assess complement activation,a CDC assay may be performed (see, for example, Gazzano-Santoro et al.,J. Immunol. Methods 202:163 (1996); Cragg, M. S. et al., Blood 101:1045-1052 (2003); and Cragg, M. S. and M. J. Glennie, Blood103:2738-2743 (2004)). FcRn binding and in vivo clearance/half lifedeterminations can also be performed using methods known in the art(see, for example, Petkova, S. B. et al., Int'l. Immunol.18(12):1759-1769 (2006)).

Other antibody variants having one or more amino acid substitutions areprovided. Sites of interest for substitutional mutagenesis include thehypervariable regions, but FR alterations are also contemplated.Conservative substitutions are shown in Table 1 under the heading of“preferred substitutions.” More substantial changes, denominated“exemplary substitutions” are provided in Table 1, or as furtherdescribed below in reference to amino acid classes. Amino acidsubstitutions may be introduced into an antibody of interest and theproducts screened, e.g., for a desired activity, such as improvedantigen binding, decreased immunogenicity, improved ADCC or CDC, etc.

TABLE 1 Original Exemplary Preferred Residue Substitutions SubstitutionsAla (A) Val; Leu; Ile Val Arg (R) Lys; Gln; Asn Lys Asn (N) Gln; His;Lys; Arg Gln Asp (D) Glu; Asn Glu Cys (C) Ser; Ala Ser Gln (Q) Asn;GluAsn Glu (E) Asp; Gln Asp Gly (G) Ala Ala His (H) Asn; Gln; Lys; Arg ArgIle (I) Leu; Val; Met; Ala; Phe; Norleucine Leu Leu (L) Norleucine, Ile;Val; Met; Ala; Phe Ile Lys (K) Arg; Gln; Asn Arg Met (M) Leu; Phe; IleLeu Phe (F) Trp; Leu; Val; Ile; Ala; Tyr Tyr Pro (P) Ala Ala Ser (S) ThrThr Thr (T) Val; Ser Ser Trp (W) Tyr; Phe Tyr Tyr (Y) Trp; Phe; Thr; SerPhe Val (V) Ile; Leu; Met; Phe; Ala; Norleucine Leu

Modifications in the biological properties of an antibody may beaccomplished by selecting substitutions that affect (a) the structure ofthe polypeptide backbone in the area of the substitution, for example,as a sheet or helical conformation, (b) the charge or hydrophobicity ofthe molecule at the target site, or (c) the bulk of the side chain.Amino acids may be grouped according to similarities in the propertiesof their side chains (in A. L. Lehninger, in Biochemistry, second ed.,pp. 73-75, Worth Publishers, New York (1975)):

(1) non-polar: Ala (A), Val (V), Leu (L), Ile (I), Pro (P), Phe (F), Trp(W), Met (M)

(2) uncharged polar: Gly (G), Ser (S), Thr (T), Cys (C), Tyr (Y), Asn(N), Gln (O)

(3) acidic: Asp (D), Glu (E)

(4) basic: Lys (K), Arg (R), H is(H)

Alternatively, naturally occurring residues may be divided into groupsbased on common side-chain properties:

(1) hydrophobic: Norleucine, Met, Ala, Val, Leu, Ile;

(2) neutral hydrophilic: Cys, Ser, Thr, Asn, Gln;

(3) acidic: Asp, Glu;

(4) basic: His, Lys, Arg;

(5) residues that influence chain orientation: Gly, Pro;

(6) aromatic: Trp, Tyr, Phe.

Non-conservative substitutions will entail exchanging a member of one ofthese classes for another class. Such substituted residues also may beintroduced into the conservative substitution sites or, into theremaining (non-conserved) sites.

One type of substitutional variant involves substituting one or morehypervariable region residues of a parent antibody (e.g. a humanized orhuman antibody). Generally, the resulting variant(s) selected forfurther development will have modified (e.g., improved) biologicalproperties relative to the parent antibody from which they aregenerated. An exemplary substitutional variant is an affinity maturedantibody, which may be conveniently generated using phage display-basedaffinity maturation techniques. Briefly, several hypervariable regionsites (e.g. 6-7 sites) are mutated to generate all possible amino acidsubstitutions at each site. The antibodies thus generated are displayedfrom filamentous phage particles as fusions to at least part of a phagecoat protein (e.g., the gene III product of M13) packaged within eachparticle. The phage-displayed variants are then screened for theirbiological activity (e.g. binding affinity). In order to identifycandidate hypervariable region sites for modification, scanningmutagenesis (e.g., alanine scanning) can be performed to identifyhypervariable region residues contributing significantly to antigenbinding. Alternatively, or additionally, it may be beneficial to analyzea crystal structure of the antigen-antibody complex to identify contactpoints between the antibody and antigen. Such contact residues andneighboring residues are candidates for substitution according totechniques known in the art, including those elaborated herein. Oncesuch variants are generated, the panel of variants is subjected toscreening using techniques known in the art, including those describedherein, and variants with superior properties in one or more relevantassays may be selected for further development.

Nucleic acid molecules encoding amino acid sequence variants of theantibody are prepared by a variety of methods known in the art. Thesemethods include, but are not limited to, isolation from a natural source(in the case of naturally occurring amino acid sequence variants) orpreparation by oligonucleotide-mediated (or site-directed) mutagenesis,PCR mutagenesis, and cassette mutagenesis of an earlier prepared variantor a non-variant version of the antibody.

It may be desirable to introduce one or more amino acid modifications inan Fc region of antibodies of the invention, thereby generating an Fcregion variant. The Fc region variant may comprise a human Fc regionsequence (e.g., a human IgG1, IgG2, IgG3 or IgG4 Fc region) comprisingan amino acid modification (e.g. a substitution) at one or more aminoacid positions including that of a hinge cysteine.

In accordance with this description and the teachings of the art, it iscontemplated that in some embodiments, an antibody of the invention maycomprise one or more alterations as compared to the wild typecounterpart antibody, e.g. in the Fc region. These antibodies wouldnonetheless retain substantially the same characteristics required fortherapeutic utility as compared to their wild type counterpart. Forexample, it is thought that certain alterations can be made in the Fcregion that would result in altered (i.e., either improved ordiminished) C1q binding and/or Complement Dependent Cytotoxicity (CDC),e.g., as described in WO99/51642. See also Duncan & Winter, Nature322:738-40 (1988); U.S. Pat. No. 5,648,260; U.S. Pat. No. 5,624,821; andWO94/29351 concerning other examples of Fc region variants. WO00/42072(Presta) and WO 2004/056312 (Lowman) describe antibody variants withimproved or diminished binding to FcRs. The content of these patentpublications are specifically incorporated herein by reference. See,also, Shields et al. J. Biol. Chem. 9(2): 6591-6604 (2001). Antibodieswith increased half lives and improved binding to the neonatal Fcreceptor (FcRn), which is responsible for the transfer of maternal IgGsto the fetus (Guyer et al., J. Immunol. 117:587 (1976) and Kim et al.,J. Immunol. 24:249 (1994)), are described in US2005/0014934A1 (Hinton etal.). These antibodies comprise an Fc region with one or moresubstitutions therein which improve binding of the Fc region to FcRn.Polypeptide variants with altered Fc region amino acid sequences andincreased or decreased C1q binding capability are described in U.S. Pat.No. 6,194,551B1, WO99/51642. The contents of those patent publicationsare specifically incorporated herein by reference. See, also, Idusogieet al. J. Immunol. 164: 4178-4184 (2000).

In another aspect, the invention provides antibodies comprisingmodifications in the interface of Fc polypeptides comprising the Fcregion, wherein the modifications facilitate and/or promoteheterodimerization. These modifications comprise introduction of aprotuberance into a first Fc polypeptide and a cavity into a second Fcpolypeptide, wherein the protuberance is positionable in the cavity soas to promote complexing of the first and second Fc polypeptides.Methods of generating antibodies with these modifications are known inthe art, e.g., as described in U.S. Pat. No. 5,731,168.

In yet another aspect, it may be desirable to create cysteine engineeredantibodies, e.g., “thioMAbs,” and “thioFabs” in which one or moreresidues of an antibody are substituted with cysteine residues. Inparticular embodiments, the substituted residues occur at accessiblesites of the antibody. By substituting those residues with cysteine,reactive thiol groups are thereby positioned at accessible sites of theantibody and may be used to conjugate the antibody to other moieties,such as drug moieties or linker-drug moieties, as described furtherherein. In certain embodiments, any one or more of the followingresidues may be substituted with cysteine: V205 (Kabat numbering) of thelight chain; A118 (EU numbering) of the heavy chain; and S400 (EUnumbering) of the heavy chain Fc region. In a preferred embodiment, A118(EU numbering) of the heavy chain is substituted for cysteine. Cysteineengineered thioMabs and thioFabs are described in further detail hereinbelow.

E. Antibody Derivatives

The antibodies of the present invention can be further modified tocontain additional nonproteinaceous moieties that are known in the artand readily available. Preferably, the moieties suitable forderivatization of the antibody are water soluble polymers. Non-limitingexamples of water soluble polymers include, but are not limited to,polyethylene glycol (PEG), copolymers of ethylene glycol/propyleneglycol, carboxymethylcellulose, dextran, polyvinyl alcohol, polyvinylpyrrolidone, poly-1,3-dioxolane, poly-1,3,6-trioxane, ethylene/maleicanhydride copolymer, polyaminoacids (either homopolymers or randomcopolymers), and dextran or poly(n-vinyl pyrrolidone)polyethyleneglycol, propropylene glycol homopolymers, polypropylene oxide/ethyleneoxide co-polymers, polyoxyethylated polyols (e.g., glycerol), polyvinylalcohol, and mixtures thereof. Polyethylene glycol propionaldehyde mayhave advantages in manufacturing due to its stability in water. Thepolymer may be of any molecular weight, and may be branched orunbranched. The number of polymers attached to the antibody may vary,and if more than one polymer are attached, they can be the same ordifferent molecules. In general, the number and/or type of polymers usedfor derivatization can be determined based on considerations including,but not limited to, the particular properties or functions of theantibody to be improved, whether the antibody derivative will be used ina therapy under defined conditions, etc.

In another embodiment, conjugates of an antibody and nonproteinaceousmoiety that may be selectively heated by exposure to radiation areprovided. In one embodiment, the nonproteinaceous moiety is a carbonnanotube (Kam et al., PNAS USA 102: 11600-11605 (2005)). The radiationmay be of any wavelength, and includes, but is not limited to,wavelengths that do not harm ordinary cells, but which heat thenonproteinaceous moiety to a temperature at which cells proximal to theantibody-nonproteinaceous moiety are killed.

IV. Methods of Making Antibodies

A. Generating Phage-Derived Antibodies

Antibodies of the invention may be prepared by phage(mid) displaytechniques as disclosed in Lee et al., J. Mol. Biol. (2004), 340(5):1073-93). Phage(mid) display allows the generation of large libraries ofprotein variants which can be rapidly sorted for those sequences thatbind to a target molecule with high affinity. Nucleic acids encodingvariant polypeptides are generally fused to a nucleic acid sequenceencoding a viral coat protein, such as the gene III protein or the geneVIII protein. Monovalent phagemid display systems where the nucleic acidsequence encoding the protein or polypeptide is fused to a nucleic acidsequence encoding a portion of the gene III protein have been developed.(Bass, S., Proteins, 8:309 (1990); Lowman and Wells, Methods: ACompanion to Methods in Enzymology, 3:205 (1991)). In a monovalentphagemid display system, the gene fusion is expressed at low levels andwild type gene III proteins are also expressed so that infectivity ofthe particles is retained. Methods of generating peptide libraries andscreening those libraries have been disclosed in many patents (e.g. U.S.Pat. No. 5,723,286, U.S. Pat. No. 5,432,018, U.S. Pat. No. 5,580,717,U.S. Pat. No. 5,427,908 and U.S. Pat. No. 5,498,530).

Libraries of antibodies or antigen binding polypeptides have beenprepared in a number of ways including by altering a single gene byinserting random DNA sequences or by cloning a family of related genes.Methods for displaying antibodies or antigen binding fragments usingphage(mid) display have been described in U.S. Pat. Nos. 5,750,373,5,733,743, 5,837,242, 5,969,108, 6,172,197, 5,580,717, and 5,658,727.The library is then screened for expression of antibodies or antigenbinding proteins with the desired characteristics.

Methods of substituting an amino acid of choice into a template nucleicacid are well established in the art, some of which are describedherein. For example, hypervariable region residues can be substitutedusing the Kunkel method. See, e.g., Kunkel et al., Methods Enzymol.154:367-382 (1987).

The sequence of oligonucleotides includes one or more of the designedcodon sets for the hypervariable region residues to be altered. A codonset is a set of different nucleotide triplet sequences used to encodedesired variant amino acids. Codon sets can be represented using symbolsto designate particular nucleotides or equimolar mixtures of nucleotidesas shown in below according to the IUB code.

IUB CODES

G Guanine

A Adenine

T Thymine

C Cytosine

R (A or G)

Y (C or T)

M (A or C)

K (G or T)

S(C or G)

W (A or T)

H (A or C or T)

B (C or G or T)

V (A or C or G)

D (A or G or T) H

N (A or C or G or T)

For example, in the codon set DVK, D can be nucleotides A or G or T; Vcan be A or G or C; and K can be G or T. This codon set can present 18different codons and can encode amino acids Ala, Trp, Tyr, Lys, Thr,Asn, Lys, Ser, Arg, Asp, Glu, Gly, and Cys.

Oligonucleotide or primer sets can be synthesized using standardmethods. A set of oligonucleotides can be synthesized, for example, bysolid phase synthesis, containing sequences that represent all possiblecombinations of nucleotide triplets provided by the codon set and thatwill encode the desired group of amino acids. Synthesis ofoligonucleotides with selected nucleotide “degeneracy” at certainpositions is well known in that art. Such sets of nucleotides havingcertain codon sets can be synthesized using commercial nucleic acidsynthesizers (available from, for example, Applied Biosystems, FosterCity, Calif.), or can be obtained commercially (for example, from LifeTechnologies, Rockville, Md.). Therefore, a set of oligonucleotidessynthesized having a particular codon set will typically include aplurality of oligonucleotides with different sequences, the differencesestablished by the codon set within the overall sequence.Oligonucleotides, as used according to the invention, have sequencesthat allow for hybridization to a variable domain nucleic acid templateand also can include restriction enzyme sites for cloning purposes.

In one method, nucleic acid sequences encoding variant amino acids canbe created by oligonucleotide-mediated mutagenesis. This technique iswell known in the art as described by Zoller et al., Nucleic Acids Res.10:6487-6504 (1987). Briefly, nucleic acid sequences encoding variantamino acids are created by hybridizing an oligonucleotide set encodingthe desired codon sets to a DNA template, where the template is thesingle-stranded form of the plasmid containing a variable region nucleicacid template sequence. After hybridization, DNA polymerase is used tosynthesize an entire second complementary strand of the template thatwill thus incorporate the oligonucleotide primer, and will contain thecodon sets as provided by the oligonucleotide set.

Generally, oligonucleotides of at least 25 nucleotides in length areused. An optimal oligonucleotide will have 12 to 15 nucleotides that arecompletely complementary to the template on either side of thenucleotide(s) coding for the mutation(s). This ensures that theoligonucleotide will hybridize properly to the single-stranded DNAtemplate molecule. The oligonucleotides are readily synthesized usingtechniques known in the art such as that described by Crea et al., PNASUSA, 75:5765 (1978).

The DNA template is generated by those vectors that are either derivedfrom bacteriophage M13 vectors (the commercially available M13 mp18 andM13 mp19 vectors are suitable), or those vectors that contain asingle-stranded phage origin of replication as described by Viera etal., Meth. Enzymol., 153:3 (1987). Thus, the DNA that is to be mutatedcan be inserted into one of these vectors in order to generatesingle-stranded template. Production of the single-stranded template isdescribed in sections 4.21-4.41 of Sambrook et al., above.

To alter the native DNA sequence, the oligonucleotide is hybridized tothe single stranded template under suitable hybridization conditions. ADNA polymerizing enzyme, usually T7 DNA polymerase or the Klenowfragment of DNA polymerase I, is then added to synthesize thecomplementary strand of the template using the oligonucleotide as aprimer for synthesis. A heteroduplex molecule is thus formed such thatone strand of DNA encodes the mutated form of gene 1, and the otherstrand (the original template) encodes the native, unaltered sequence ofgene 1. This heteroduplex molecule is then transformed into a suitablehost cell, usually a prokaryote such as E. coli JM101. After growing thecells, they are plated onto agarose plates and screened using theoligonucleotide primer radiolabeled with a 32-Phosphate to identify thebacterial colonies that contain the mutated DNA.

The method described immediately above may be modified such that ahomoduplex molecule is created wherein both strands of the plasmidcontain the mutation(s). The modifications are as follows: The singlestranded oligonucleotide is annealed to the single-stranded template asdescribed above. A mixture of three deoxyribonucleotides,deoxyriboadenosine (dATP), deoxyriboguanosine (dGTP), anddeoxyribothymidine (dTT), is combined with a modifiedthiodeoxyribocytosine called dCTP-(aS) (which can be obtained fromAmersham). This mixture is added to the template-oligonucleotidecomplex. Upon addition of DNA polymerase to this mixture, a strand ofDNA identical to the template except for the mutated bases is generated.In addition, this new strand of DNA will contain dCTP-(aS) instead ofdCTP, which serves to protect it from restriction endonucleasedigestion. After the template strand of the double-stranded heteroduplexis nicked with an appropriate restriction enzyme, the template strandcan be digested with ExoIII nuclease or another appropriate nucleasepast the region that contains the site(s) to be mutagenized. Thereaction is then stopped to leave a molecule that is only partiallysingle-stranded. A complete double-stranded DNA homoduplex is thenformed using DNA polymerase in the presence of all fourdeoxyribonucleotide triphosphates, ATP, and DNA ligase. This homoduplexmolecule can then be transformed into a suitable host cell.

As indicated previously the sequence of the oligonucleotide set is ofsufficient length to hybridize to the template nucleic acid and mayalso, but does not necessarily, contain restriction sites. The DNAtemplate can be generated by those vectors that are either derived frombacteriophage M13 vectors or vectors that contain a single-strandedphage origin of replication as described by Viera et al., Meth.Enzymol., 153:3 (1987). Thus, the DNA that is to be mutated must beinserted into one of these vectors in order to generate single-strandedtemplate. Production of the single-stranded template is described insections 4.21-4.41 of Sambrook et al., supra.

According to another method, a library can be generated by providingupstream and downstream oligonucleotide sets, each set having aplurality of oligonucleotides with different sequences, the differentsequences established by the codon sets provided within the sequence ofthe oligonucleotides. The upstream and downstream oligonucleotide sets,along with a variable domain template nucleic acid sequence, can be usedin a polymerase chain reaction to generate a “library” of PCR products.The PCR products can be referred to as “nucleic acid cassettes”, as theycan be fused with other related or unrelated nucleic acid sequences, forexample, viral coat proteins and dimerization domains, using establishedmolecular biology techniques.

The sequence of the PCR primers includes one or more of the designedcodon sets for the solvent accessible and highly diverse positions in ahypervariable region. As described above, a codon set is a set ofdifferent nucleotide triplet sequences used to encode desired variantamino acids.

Antibody selectants that meet the desired criteria, as selected throughappropriate screening/selection steps can be isolated and cloned usingstandard recombinant techniques.

In one aspect, the HVR-H1, HVR-H2, HVR-H3 sequences are varied byholding amino acids at particular positions constant and varying theamino acids at other positions.

In one aspect, the invention provides an antibody comprising at leastone, at least two, or all three of the following:

(i) a HVR-L1 sequence comprising the sequence of SEQ ID NO:1;

(ii) a HVR-L2 sequence comprising the sequence of SEQ ID NO:2;

(iii) a HVR-L3 sequence comprising the sequence of SEQ ID NO:3.

The amino acid sequences of SEQ ID NOS:1, 2, and 3 are numbered withrespect to individual HVR (i.e., L1, L2, or L3) as indicated in by inFIGS. 1A (positions 24-34, 50-56, and 89-97, respectively) and 2A(positions 24-34, 50-56, and 89-97, respectively), the numbering beingconsistent with the Kabat numbering system as described below.

In one aspect, the invention provides an antibody comprising at leastone, at least two, or all three of the following:

(i) a HVR-H1 sequence comprising the sequence of SEQ ID NO: 4;

(ii) a HVR-H2 sequence comprising the sequence of SEQ ID NO:5;

(iii) a HVR-H3 sequence comprising the sequence of SEQ ID NO:6.

The amino acid sequences of SEQ ID NOS:4, 5, and 6 are numbered withrespect to individual HVR (i.e., H1, H2 or H3) as indicated in by inFIGS. 1B (positions 26-35, 49-65, and 93-102, respectively) and 2B(positions 26-35, 49-65, and 93-102, respectively), the numbering beingconsistent with the Kabat numbering system as described below.

In one aspect, the invention provides antibodies comprising light chainHVR sequences as depicted in FIGS. 1A and 2A.

In one aspect, the invention provides antibodies comprising heavy chainHVR sequences as depicted in FIGS. 1B and 2B.

Some embodiments of antibodies of the invention comprise a light chainvariable domain of humanized 4D5 antibody (huMAb4D5-8) (HERCEPTIN®anti-HER2 antibody, Genentech, Inc., South San Francisco, Calif., USA)(also referred to in U.S. Pat. No. 6,407,213 and Lee et al., J. Mol.Biol. (2004), 340(5):1073-93) as depicted in SEQ ID NO:98 below.

(SEQ ID NO: 98) 1 Asp Ile Gln Met Thr Gln Ser Pro Ser Ser Leu SerAla Ser Val Gly Asp Arg Val Thr Ile Thr Cys Arg Ala Ser Gln Asp Val 

 Thr Ala Val Ala Trp Tyr Gln Gln Lys Pro Gly Lys Ala Pro Lys Leu Leu IleTyr Ser Ala Ser Phe Leu Tyr Ser Gly Val Pro Ser Arg Phe Ser Gly Ser 

 Ser Gly Thr Asp Phe Thr Leu Thr Ile Ser Ser Leu Gln Pro Glu Asp Phe AlaThr Tyr Tyr Cys Gln Gln 

 Tyr Thr Thr Pro Pro Thr Phe Gly Gln Gly Thr Lys Val Glu Ile Lys 107

(HVR Residues are Underlined)

In one embodiment, the huMAb4D5-8 light chain variable domain sequenceis modified at one or more of positions 30, 66 and 91 (Asn, Arg and Hisas indicated in bold/italics above, respectively). In one embodiment,the modified huMAb4D5-8 sequence comprises Ser in position 30, Gly inposition 66 and/or Ser in position 91. Accordingly, in one embodiment,an antibody of the invention comprises a light chain variable domaincomprising the sequence depicted in SEQ ID NO:167 below:

(SEQ ID NO: 167) 1 Asp Ile Gln Met Thr Gln Ser Pro Ser Ser Leu SerAla Ser Val Gly Asp Arg Val Thr Ile Thr Cys Arg Ala Ser Gln Asp Val 

 Thr Ala Val Ala Trp Tyr Gln Gln Lys Pro Gly Lys Ala Pro Lys Leu Leu IleTyr Ser Ala Ser Phe Leu Tyr Ser Gly Val Pro Ser Arg Phe Ser Gly Ser 

 Ser Gly Thr Asp Phe Thr Leu Thr Ile Ser Ser Leu Gln Pro Glu Asp Phe AlaThr Tyr Tyr Cys Gln Gln 

Ser Tyr Thr Thr Pro Pro Thr Phe Gly Gln Gly Thr Lys Val Glu Ile Lys 107

(HVR Residues are Underlined)

Substituted residues with respect to huMAb4D5-8 are indicated inbold/italics above.

Antibodies of the invention can comprise any suitable framework variabledomain sequence, provided binding activity to Robo4 is substantiallyretained, such as at least 1%, at least 10%, at least 20%, at least 30%,at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, atleast 90%, at least 100% or greater binding activity relative to anantibody of the invention disclosed herein. For example, in someembodiments, antibodies of the invention comprise a human subgroup IIIheavy chain framework consensus sequence. In one embodiment of theseantibodies, the framework consensus sequence comprises substitution atposition 71, 73 and/or 78. In some embodiments of these antibodies,position 71 is A, 73 is T and/or 78 is A. In one embodiment, theseantibodies comprise heavy chain variable domain framework sequences ofhuMAb4D5-8 (HERCEPTIN®, Genentech, Inc., South San Francisco, Calif.,USA) (also referred to in U.S. Pat. Nos. 6,407,213 and 5,821,337, andLee et al., J. Mol. Biol. 340(5): 1073-93 (2004)). In one embodiment,these antibodies further comprise a human κI light chain frameworkconsensus sequence. In one embodiment, these antibodies comprise lightchain HVR sequences of huMAb4D5-8 as described in U.S. Pat. Nos.6,407,213 and 5,821,337.) In one embodiment, these antibodies compriselight chain variable domain sequences of huMAb4D5-8 (SEQ ID NOS: 98 or167) (HERCEPTIN® anti-HER2 antibody, Genentech, Inc., South SanFrancisco, Calif., USA) (also referred to in U.S. Pat. Nos. 6,407,213 &5,821,337, and Lee et al., J. Mol. Biol. 340(5):1073-93 (2004)).

In one embodiment, antibodies of the invention may comprise frameworkregion sequences of huMAb4D5-8 light and heavy chains as provided below(SEQ ID NOS:9, 10, 168, 12 (light chain) and SEQ ID NOS:13, 14, 15, 16(heavy chain)). Numbers in superscript/bold indicate amino acidpositions according to Kabat.

Framework Sequences of huMAb4D5-8 Light Chain

LC-FR1 (SEQ ID NO: 9) ¹Asp Ile Gln Met Thr Gln Ser Pro Ser Ser Leu SerAla Ser Val Gly Asp Arg Val Thr Ile Thr Cys²³ LC-FR2 (SEQ ID NO: 10)³⁵Trp Tyr Gln Gln Lys Pro Gly Lys Ala Pro Lys Leu Leu Ile Tyr⁴⁹ LC-FR3(SEQ ID NO: 168) ⁵⁷Gly Val Pro Ser Arg Phe Ser Gly Ser Arg Ser GlyThr As Phe Thr Leu Thr Ile Ser Ser Leu Gln Pro GluAsp Phe Ala Thr Tyr Tyr Cys⁸ LC-FR4 (SEQ ID NO: 12)⁹⁸Phe Gly Gln Gly Thr Lys Val Glu Ile Lys¹⁹⁷ Framework Sequences of huMAb4D5-8 Heavy Chain

HC-FR1 (SEQ ID NO: 13) ¹Glu Val Gln Leu Val Glu Ser Gly Gly Gly Leu ValGln Pro Gly Gly Ser Leu Arg Leu Ser Cys Ala Ala Ser²⁵  HC-FR2(SEQ ID NO: 14) ³⁶Trp Val Arg Gln Ala Pro Gly Lys Gly Leu Glu Trp Val⁴⁸ HC-FR3 (SEQ ID NO: 15) ⁶⁶Arg Phe Thr Ile Ser Ala Asp Thr Ser Lys Asn ThrAla Tyr Leu Gln Met Asn^(82a) Ser^(82b) Leu^(82c) Arg⁸³ AlaGlu Asp Thr Ala Val Tyr Tyr Cys⁹²  HC-FR4 (SEQ ID NO: 16)¹⁰³Trp Gly Gln Gly Thr Leu Val Thr Val Ser Ser¹¹³

In one embodiment, antibodies of the invention may comprisemodified/variant_framework region sequences of huMAb4D5-8 light andheavy chains as provided below (SEQ ID NOS:9, 10, 11, 12 (light chain)and SEQ ID NOS: 13, 14, 15, 16 (heavy chain)). Numbers insuperscript/bold indicate amino acid positions according to Kabat.

Framework sequences of huMAb4D5-8 Light Chain Modified at Position 66(Underlined)

LC-FR1 (SEQ ID NO: 9) ¹Asp Ile Gln Met Thr Gln Ser Pro Ser Ser Leu SerAla Ser Val Gly Asp Arg Val Thr Ile Thr Cys²³  LC-FR2 (SEQ ID NO: 10)³⁵Trp Tyr Gln Gln Lys Pro Gly Lys Ala Pro Lys Leu Leu Ile Tyr⁴⁹ LC-FR3(SEQ ID NO: 11) ⁵⁷G1y Val Pro Ser Arg Phe Ser Gly Ser Gly Ser GlyThr Asp Phe Thr Leu Thr Ile Ser Ser Leu Gln ProGlu Asp Phe Ala Thr Tyr Tyr Cys⁸⁸ LC-FR4 (SEQ ID NO: 12)⁹⁸Phe Gly Gln Gly Thr Lys Val Glu Ile Lys¹⁰⁷Framework Sequences of huMAb4D5-8 Heavy Chain Modified at Positions 71,73 and 78 (Underlined)

HC-FR1 (SEQ ID NO: 13) ¹Glu Val Gln Leu Val Glu Ser Gly Gly Gly Leu ValGln Pro Gly Gly Ser Leu Arg Leu Ser Cys Ala Ala Ser²⁵ HC-FR2(SEQ ID NO: 14) ³⁶Trp Val Arg Gln Ala Pro Gly Lys Gly Leu Glu Trp Val⁴⁸HC-FR3 (SEQ ID NO: 15) ⁶⁶Arg Phe Thr Ile Ser Arg Asp Asn Ser Lys Asn ThrLeu Tyr Leu Gln Met Asn^(82a) Ser^(82b) Leu^(82c) Arg⁸³ AlaGlu Asp Thr Ala Val Tyr Tyr Cys⁹² HC-FR4 (SEQ ID NO: 16)¹⁰³Trp Gly Gln Gly Thr Leu Val Thr Val Ser Ser¹¹³

In one embodiment, an antibody of the invention is affinity matured toobtain the target binding affinity desired. In one example, an affinitymatured antibody of the invention comprises substitution at amino acidpositions of the light chain as follows. In one embodiment, a variantHVR-L1 A1-A11 (Kabat positions 24-34) is RASQDVSTAVA (SEQ ID NO:1)having 1, 2, 3, 4, or 5 substitutions in any combination of thefollowing positions: A6 (G), A7 (A), A8 (R or I), A9 (S or Y), and A10(L). In one embodiment, a variant HVR-L2 B1-B7 (Kabat positions 50-56)is SASFLYS (SEQ ID NO:2) having 1, 2, 3, 4, or 5 substitutions in anycombination of the following positions: B3 (T), B4 (L, N or T), B5 (E orA), B6 (A or S), and B7 (Y or a deletion). In one embodiment, a variantHVR-L3 C1-C9 (Kabat positions 89-97) is QQSYTTPPT (SEQ ID NO:3) having1, 2, 3, 4, 5 or 6 substitutions in any combination of the followingpositions: C3 (P, T, F, or G), C4 (F, R, or N), CS (A, S, D, F, H, N, V,or G), C6 (A, D, N, L, I, M, Y, or G), C7 (L, H, or T), and C8 (A, M, F,or S).

In one embodiment, an antibody of the affinity matured antibody of theinvention comprises substitution at amino acid positions of the heavychain as follows. In one embodiment, a variant HVR-H1 D1-D10 (Kabatpositions 26-35) is GFTINGYYIH (SEQ ID NO:17) having 1, 2, 3, 4, or 5substitutions in any combination of the following positions: D3 (S), D4(L), D5 (Y, D, or K), D9 (F, L or N), and D10 (E or Q). In oneembodiment, a variant HVR-H2 E1-E18 (Kabat positions 49-65) isGFIYPAGGDTDYADSVKG (SEQ ID NO:18) having 1, 2, 3, 4, or 5 substitutionsin any combination of the following positions: E2 (R), E5 (S), E7 (L),E9 (H, K, A, or V), and E11 (A, E or I). In one embodiment, HVR-H3F1-F18 (Kabat positions 93-102) is ARLIGNKFGWSSYG*MDY (SEQ ID NO:19),wherein “*” in the amino acid sequence indicates a deletion at positionF15, Kabat position 100).

In one embodiment, the affinity matured antibody of the inventioncomprises one, two or three HVRs (L1, L2, and/or L3) depicted in FIG.2A. In one embodiment, the affinity matured antibody of the inventioncomprises one, two, or three HVRs (H1, H2, and/or H3) depicted in FIG.2B. In one embodiment, the affinity matured antibody of the inventioncomprises one, two, three, four, five, or all six HVRs selected from theHVRs depicted in FIGS. 2A and 2B.

In one embodiment, the affinity matured antibody of the inventioncomprises the light chain variable region sequence of any of thesequences depicted in FIG. 2A. In one embodiment, the affinity maturedantibody of the invention comprises the heavy chain variable regionsequence of any of the sequences depicted in FIG. 2B.

In one embodiment, the affinity matured antibody of the inventioncomprises a light chain variable region sequence (comprising frameworksequences and HVR sequences) shown in FIG. 2A and the heavy chainvariable region sequences (comprising framework sequences and HVRsequences) of the corresponding antibody shown in FIG. 2B.

In one aspect, the invention provides an antibody that competes with anyof the above-mentioned antibodies for binding to Robo4. In one aspect,the invention provides an antibody that binds to the same epitope onRobo4 as any of the above-mentioned antibodies.

B. Hybridoma-Based Methods

Monoclonal antibodies of the invention can also be made using thehybridoma method first described by Kohler et al., Nature, 256:495(1975), and further described, e.g., in Hongo et al., Hybridoma, 14 (3):253-260 (1995), Harlow et al., Antibodies: A Laboratory Manual, (ColdSpring Harbor Laboratory Press, 2nd ed. 1988); Hammerling et al., in:Monoclonal Antibodies and T-Cell Hybridomas 563-681 (Elsevier, N.Y.,1981), and Ni, Xiandai Mianyixue, 26(4):265-268 (2006) regardinghuman-human hybridomas. Additional methods include those described, forexample, in U.S. Pat. No. 7,189,826 regarding production of monoclonalhuman natural IgM antibodies from hybridoma cell lines. Human hybridomatechnology (Trioma technology) is described in Vollmers and Brandlein,Histology and Histopathology, 20(3):927-937 (2005) and Vollmers andBrandlein, Methods and Findings in Experimental and ClinicalPharmacology, 27(3): 185-91 (2005). Other hybridoma techniques, see,e.g., US 2006/258841; US 2006/183887 (fully human antibodies), US2006/059575; US 2005/287149; US 2005/100546; US 2005/026229; and U.S.Pat. Nos. 7,078,492 and 7,153,507.

C. Vectors, Host Cells, and Recombinant Methods

Antibodies may also be produced using recombinant methods. Forrecombinant production of an anti-Robo4 antibody, nucleic acid encodingthe antibody is isolated and inserted into a replicable vector forfurther cloning (amplification of the DNA) or for expression. DNAencoding the antibody may be readily isolated and sequenced usingconventional procedures (e.g., by using oligonucleotide probes that arecapable of binding specifically to genes encoding the heavy and lightchains of the antibody). Many vectors are available. The vectorcomponents generally include, but are not limited to, one or more of thefollowing: a signal sequence, an origin of replication, one or moremarker genes, an enhancer element, a promoter, and a transcriptiontermination sequence.

1. Signal Sequence Component

An antibody of the invention may be produced recombinantly not onlydirectly, but also as a fusion polypeptide with a heterologouspolypeptide, which is preferably a signal sequence or other polypeptidehaving a specific cleavage site at the N-terminus of the mature proteinor polypeptide. The heterologous signal sequence selected preferably isone that is recognized and processed (i.e., cleaved by a signalpeptidase) by the host cell. For prokaryotic host cells that do notrecognize and process a native antibody signal sequence, the signalsequence is substituted by a prokaryotic signal sequence selected, forexample, from the group of the alkaline phosphatase, penicillinase, lpp,or heat-stable enterotoxin II leaders. For yeast secretion the nativesignal sequence may be substituted by, e.g., the yeast invertase leader,α factor leader (including Saccharomyces and Kluyveromyces α-factorleaders), or acid phosphatase leader, the C. albicans glucoamylaseleader, or the signal described in WO 90/13646. In mammalian cellexpression, mammalian signal sequences as well as viral secretoryleaders, for example, the herpes simplex gD signal, are available.

2. Origin of Replication

Both expression and cloning vectors contain a nucleic acid sequence thatenables the vector to replicate in one or more selected host cells.Generally, in cloning vectors this sequence is one that enables thevector to replicate independently of the host chromosomal DNA, andincludes origins of replication or autonomously replicating sequences.Such sequences are well known for a variety of bacteria, yeast, andviruses. The origin of replication from the plasmid pBR322 is suitablefor most Gram-negative bacteria, the 2μ plasmid origin is suitable foryeast, and various viral origins (SV40, polyoma, adenovirus, VSV or BPV)are useful for cloning vectors in mammalian cells. Generally, the originof replication component is not needed for mammalian expression vectors(the SV40 origin may typically be used only because it contains theearly promoter).

3. Selection Gene Component

Expression and cloning vectors may contain a selection gene, also termeda selectable marker. Typical selection genes encode proteins that (a)confer resistance to antibiotics or other toxins, e.g., ampicillin,neomycin, methotrexate, or tetracycline, (b) complement auxotrophicdeficiencies, or (c) supply critical nutrients not available fromcomplex media, e.g., the gene encoding D-alanine racemase for Bacilli.

One example of a selection scheme utilizes a drug to arrest growth of ahost cell. Those cells that are successfully transformed with aheterologous gene produce a protein conferring drug resistance and thussurvive the selection regimen. Examples of such dominant selection usethe drugs neomycin, mycophenolic acid and hygromycin.

Another example of suitable selectable markers for mammalian cells arethose that enable the identification of cells competent to take upantibody-encoding nucleic acid, such as DHFR, glutamine synthetase (GS),thymidine kinase, metallothionein-I and -II, preferably primatemetallothionein genes, adenosine deaminase, ornithine decarboxylase,etc.

For example, cells transformed with the DHFR gene are identified byculturing the transformants in a culture medium containing methotrexate(Mtx), a competitive antagonist of DHFR. Under these conditions, theDHFR gene is amplified along with any other co-transformed nucleic acid.A Chinese hamster ovary (CHO) cell line deficient in endogenous DHFRactivity (e.g., ATCC CRL-9096) may be used.

Alternatively, cells transformed with the GS gene are identified byculturing the transformants in a culture medium containing L-methioninesulfoximine (Msx), an inhibitor of GS. Under these conditions, the GSgene is amplified along with any other co-transformed nucleic acid. TheGS selection/amplification system may be used in combination with theDHFR selection/amplification system described above.

Alternatively, host cells (particularly wild-type hosts that containendogenous DHFR) transformed or co-transformed with DNA sequencesencoding an antibody of interest, wild-type DHFR gene, and anotherselectable marker such as aminoglycoside 3′-phosphotransferase (APH) canbe selected by cell proliferation in medium containing a selection agentfor the selectable marker such as an aminoglycosidic antibiotic, e.g.,kanamycin, neomycin, or G418. See U.S. Pat. No. 4,965,199.

A suitable selection gene for use in yeast is the trp1 gene present inthe yeast plasmid YRp7 (Stinchcomb et al., Nature, 282:39 (1979)). Thetrp1 gene provides a selection marker for a mutant strain of yeastlacking the ability to grow in tryptophan, for example, ATCC No. 44076or PEP4-1. Jones, Genetics, 85:12 (1977). The presence of the trp1lesion in the yeast host cell genome then provides an effectiveenvironment for detecting transformation by growth in the absence oftryptophan. Similarly, Leu2-deficient yeast strains (ATCC 20,622 or38,626) are complemented by known plasmids bearing the Leu2 gene.

In addition, vectors derived from the 1.6 μm circular plasmid pKD1 canbe used for transformation of Kluyveromyces yeasts. Alternatively, anexpression system for large-scale production of recombinant calfchymosin was reported for K. lactis. Van den Berg, Bio/Technology, 8:135(1990). Stable multi-copy expression vectors for secretion of maturerecombinant human serum albumin by industrial strains of Kluyveromyceshave also been disclosed. Fleer et al., Bio/Technology, 9:968-975(1991).

4. Promoter Component

Expression and cloning vectors generally contain a promoter that isrecognized by the host organism and is operably linked to nucleic acidencoding an antibody. Promoters suitable for use with prokaryotic hostsinclude the phoA promoter, β-lactamase and lactose promoter systems,alkaline phosphatase promoter, a tryptophan (trp) promoter system, andhybrid promoters such as the tac promoter. However, other knownbacterial promoters are suitable. Promoters for use in bacterial systemsalso will contain a Shine-Dalgarno (S.D.) sequence operably linked tothe DNA encoding an antibody.

Promoter sequences are known for eukaryotes. Virtually all eukaryoticgenes have an AT-rich region located approximately 25 to 30 basesupstream from the site where transcription is initiated. Anothersequence found 70 to 80 bases upstream from the start of transcriptionof many genes is a CNCAAT region where N may be any nucleotide. At the3′ end of most eukaryotic genes is an AATAAA sequence that may be thesignal for addition of the poly A tail to the 3′ end of the codingsequence. All of these sequences are suitably inserted into eukaryoticexpression vectors.

Examples of suitable promoter sequences for use with yeast hosts includethe promoters for 3-phosphoglycerate kinase or other glycolytic enzymes,such as enolase, glyceraldehyde-3-phosphate dehydrogenase, hexokinase,pyruvate decarboxylase, phospho-fructokinase, glucose-6-phosphateisomerase, 3-phosphoglycerate mutase, pyruvate kinase, triosephosphateisomerase, phosphoglucose isomerase, and glucokinase.

Other yeast promoters, which are inducible promoters having theadditional advantage of transcription controlled by growth conditions,are the promoter regions for alcohol dehydrogenase 2, isocytochrome C,acid phosphatase, degradative enzymes associated with nitrogenmetabolism, metallothionein, glyceraldehyde-3-phosphate dehydrogenase,and enzymes responsible for maltose and galactose utilization. Suitablevectors and promoters for use in yeast expression are further describedin EP 73,657. Yeast enhancers also are advantageously used with yeastpromoters.

Antibody transcription from vectors in mammalian host cells can becontrolled, for example, by promoters obtained from the genomes ofviruses such as polyoma virus, fowlpox virus, adenovirus (such asAdenovirus 2), bovine papilloma virus, avian sarcoma virus,cytomegalovirus, a retrovirus, hepatitis-B virus, Simian Virus 40(SV40), or from heterologous mammalian promoters, e.g., the actinpromoter or an immunoglobulin promoter, from heat-shock promoters,provided such promoters are compatible with the host cell systems.

The early and late promoters of the SV40 virus are conveniently obtainedas an SV40 restriction fragment that also contains the SV40 viral originof replication. The immediate early promoter of the humancytomegalovirus is conveniently obtained as a HindIII E restrictionfragment. A system for expressing DNA in mammalian hosts using thebovine papilloma virus as a vector is disclosed in U.S. Pat. No.4,419,446. A modification of this system is described in U.S. Pat. No.4,601,978. See also Reyes et al., Nature 297:598-601 (1982) onexpression of human β-interferon cDNA in mouse cells under the controlof a thymidine kinase promoter from herpes simplex virus. Alternatively,the Rous Sarcoma Virus long terminal repeat can be used as the promoter.

5. Enhancer Element Component

Transcription of a DNA encoding an antibody of this invention by highereukaryotes is often increased by inserting an enhancer sequence into thevector. Many enhancer sequences are now known from mammalian genes(globin, elastase, albumin, α-fetoprotein, and insulin). Typically,however, one will use an enhancer from a eukaryotic cell virus. Examplesinclude the SV40 enhancer on the late side of the replication origin (bp100-270), the cytomegalovirus early promoter enhancer, the polyomaenhancer on the late side of the replication origin, and adenovirusenhancers. See also Yaniv, Nature 297:17-18 (1982) on enhancing elementsfor activation of eukaryotic promoters. The enhancer may be spliced intothe vector at a position 5′ or 3′ to the antibody-encoding sequence, butis preferably located at a site 5′ from the promoter.

6. Transcription Termination Component

Expression vectors used in eukaryotic host cells (yeast, fungi, insect,plant, animal, human, or nucleated cells from other multicellularorganisms) will also contain sequences necessary for the termination oftranscription and for stabilizing the mRNA. Such sequences are commonlyavailable from the 5′ and, occasionally 3′, untranslated regions ofeukaryotic or viral DNAs or cDNAs. These regions contain nucleotidesegments transcribed as polyadenylated fragments in the untranslatedportion of the mRNA encoding antibody. One useful transcriptiontermination component is the bovine growth hormone polyadenylationregion. See WO94/11026 and the expression vector disclosed therein.

7. Selection and Transformation of Host Cells

Suitable host cells for cloning or expressing the DNA in the vectorsherein are the prokaryote, yeast, or higher eukaryote cells describedabove. Suitable prokaryotes for this purpose include eubacteria, such asGram-negative or Gram-positive organisms, for example,Enterobacteriaceae such as Escherichia, e.g., E. coli, Enterobacter,Erwinia, Klebsiella, Proteus, Salmonella, e.g., Salmonella typhimurium,Serratia, e.g., Serratia marcescans, and Shigella, as well as Bacillisuch as B. subtilis and B. licheniformis (e.g., B. licheniformis 41Pdisclosed in DD 266,710 published 12 Apr. 1989), Pseudomonas such as P.aeruginosa, and Streptomyces. One preferred E. coli cloning host is E.coli 294 (ATCC 31,446), although other strains such as E. coli B, E.coli X1776 (ATCC 31,537), and E. coli W3110 (ATCC 27,325) are suitable.These examples are illustrative rather than limiting.

Full length antibody, antibody fusion proteins, and antibody fragmentscan be produced in bacteria, in particular when glycosylation and Fceffector function are not needed, such as when the therapeutic antibodyis conjugated to a cytotoxic agent (e.g., a toxin) that by itself showseffectiveness in tumor cell destruction. Full length antibodies havegreater half life in circulation. Production in E. coli is faster andmore cost efficient. For expression of antibody fragments andpolypeptides in bacteria, see, e.g., U.S. Pat. No. 5,648,237 (Carter et.al.), U.S. Pat. No. 5,789,199 (Joly et al.), U.S. Pat. No. 5,840,523(Simmons et al.), which describes translation initiation region (TIR)and signal sequences for optimizing expression and secretion. See alsoCharlton, Methods in Molecular Biology, Vol. 248 (B.K.C. Lo, ed., HumanaPress, Totowa, N.J., 2003), pp. 245-254, describing expression ofantibody fragments in E. coli. After expression, the antibody may beisolated from the E. coli cell paste in a soluble fraction and can bepurified through, e.g., a protein A or G column depending on theisotype. Final purification can be carried out similar to the processfor purifying antibody expressed e.g., in CHO cells.

In addition to prokaryotes, eukaryotic microbes such as filamentousfungi or yeast are suitable cloning or expression hosts forantibody-encoding vectors. Saccharomyces cerevisiae, or common baker'syeast, is the most commonly used among lower eukaryotic hostmicroorganisms. However, a number of other genera, species, and strainsare commonly available and useful herein, such as Schizosaccharomycespombe; Kluyveromyces hosts such as, e.g., K. lactis, K. fragilis (ATCC12,424), K. bulgaricus (ATCC 16,045), K. wickeramii (ATCC 24,178), K.waltii (ATCC 56,500), K. drosophilarum (ATCC 36,906), K. thermotolerans,and K. marxianus; yarrowia (EP 402,226); Pichia pastoris (EP 183,070);Candida; Trichoderma reesia (EP 244,234); Neurospora crassa;Schwanniomyces such as Schwanniomyces occidentalis; and filamentousfungi such as, e.g., Neurospora, Penicillium, Tolypocladium, andAspergillus hosts such as A. nidulans and A. niger. For a reviewdiscussing the use of yeasts and filamentous fungi for the production oftherapeutic proteins, see, e.g., Gerngross, Nat. Biotech. 22:1409-1414(2004).

Certain fungi and yeast strains may be selected in which glycosylationpathways have been “humanized,” resulting in the production of anantibody with a partially or fully human glycosylation pattern. See,e.g., Li et al., Nat. Biotech. 24:210-215 (2006) (describinghumanization of the glycosylation pathway in Pichia pastoris); andGerngross et al., supra.

Suitable host cells for the expression of glycosylated antibody are alsoderived from multicellular organisms (invertebrates and vertebrates).Examples of invertebrate cells include plant and insect cells. Numerousbaculoviral strains and variants and corresponding permissive insecthost cells from hosts such as Spodoptera frugiperda (caterpillar), Aedesaegypti (mosquito), Aedes albopictus (mosquito), Drosophila melanogaster(fruitfly), and Bombyx mori have been identified. A variety of viralstrains for transfection are publicly available, e.g., the L-1 variantof Autographa californica NPV and the Bm-5 strain of Bombyx mori NPV,and such viruses may be used as the virus herein according to thepresent invention, particularly for transfection of Spodopterafrugiperda cells.

Plant cell cultures of cotton, corn, potato, soybean, petunia, tomato,duckweed (Lemnaceae), alfalfa (M. truncatula), and tobacco can also beutilized as hosts. See, e.g., U.S. Pat. Nos. 5,959,177, 6,040,498,6,420,548, 7,125,978, and 6,417,429 (describing PLANTIBODIES™ technologyfor producing antibodies in transgenic plants).

Vertebrate cells may be used as hosts, and propagation of vertebratecells in culture (tissue culture) has become a routine procedure.Examples of useful mammalian host cell lines are monkey kidney CV1 linetransformed by SV40 (COS-7, ATCC CRL 1651); human embryonic kidney line(293 or 293 cells subcloned for growth in suspension culture, Graham etal., J. Gen Virol. 36:59 (1977)); baby hamster kidney cells (BHK, ATCCCCL 10); mouse sertoli cells (TM4, Mather, Biol. Reprod. 23:243-251(1980)); monkey kidney cells (CV1 ATCC CCL 70); African green monkeykidney cells (VERO-76, ATCC CRL-1587); human cervical carcinoma cells(HELA, ATCC CCL 2); canine kidney cells (MDCK, ATCC CCL 34); buffalo ratliver cells (BRL 3A, ATCC CRL 1442); human lung cells (W138, ATCC CCL75); human liver cells (Hep G2, HB 8065); mouse mammary tumor (MMT060562, ATCC CCL51); TR1 cells (Mather et al., Annals N.Y. Acad. Sci.383:44-68 (1982)); MRC 5 cells; FS4 cells; and a human hepatoma line(Hep G2). Other useful mammalian host cell lines include Chinese hamsterovary (CHO) cells, including DHFR-CHO cells (Urlaub et al., PNAS USA77:4216 (1980)); and myeloma cell lines such as NSO and Sp2/0. For areview of certain mammalian host cell lines suitable for antibodyproduction, see, e.g., Yazaki and Wu, Methods in Molecular Biology, Vol.248 (B. K. C. Lo, ed., Humana Press, Totowa, N.J., 2003), pp. 255-268.

Host cells are transformed with the above-described expression orcloning vectors for antibody production and cultured in conventionalnutrient media modified as appropriate for inducing promoters, selectingtransformants, or amplifying the genes encoding the desired sequences.

8. Culturing the Host Cells

The host cells used to produce an antibody of this invention may becultured in a variety of media. Commercially available media such asHam's F10 (Sigma), Minimal Essential Medium ((MEM), (Sigma), RPMI-1640(Sigma), and Dulbecco's Modified Eagle's Medium ((DMEM), Sigma) aresuitable for culturing the host cells. In addition, any of the mediadescribed in Ham et al., Meth. Enz. 58:44 (1979), Barnes et al., Anal.Biochem. 102:255 (1980), U.S. Pat. Nos. 4,767,704; 4,657,866; 4,927,762;4,560,655; or 5,122,469; WO 90/03430; WO 87/00195; or U.S. Pat. Re.30,985 may be used as culture media for the host cells. Any of thesemedia may be supplemented as necessary with hormones and/or other growthfactors (such as insulin, transferrin, or epidermal growth factor),salts (such as sodium chloride, calcium, magnesium, and phosphate),buffers (such as HEPES), nucleotides (such as adenosine and thymidine),antibiotics (such as GENTAMYCIN™ drug), trace elements (defined asinorganic compounds usually present at final concentrations in themicromolar range), and glucose or an equivalent energy source. Any othernecessary supplements may also be included at appropriate concentrationsthat would be known to those skilled in the art. The culture conditions,such as temperature, pH, and the like, are those previously used withthe host cell selected for expression, and will be apparent to theordinarily skilled artisan.

9. Purification of Antibodies

When using recombinant techniques, the antibody can be producedintracellularly, in the periplasmic space, or directly secreted into themedium. If the antibody is produced intracellularly, as a first step,the particulate debris, either host cells or lysed fragments, areremoved, for example, by centrifugation or ultrafiltration. Carter etal., Bio/Technology 10: 163-167 (1992) describe a procedure forisolating antibodies which are secreted to the periplasmic space of E.coli. Briefly, cell paste is thawed in the presence of sodium acetate(pH 3.5), EDTA, and phenylmethylsulfonylfluoride (PMSF) over about 30min. Cell debris can be removed by centrifugation. Where the antibody issecreted into the medium, supernatants from such expression systems aregenerally first concentrated using a commercially available proteinconcentration filter, for example, an Amicon or Millipore Pelliconultrafiltration unit. A protease inhibitor such as PMSF may be includedin any of the foregoing steps to inhibit proteolysis and antibiotics maybe included to prevent the growth of adventitious contaminants.

The antibody composition prepared from the cells can be purified using,for example, hydroxylapatite chromatography, hydrophobic interactionchromatography, gel electrophoresis, dialysis, and affinitychromatography, with affinity chromatography being among one of thetypically preferred purification steps. The suitability of protein A asan affinity ligand depends on the species and isotype of anyimmunoglobulin Fc domain that is present in the antibody. Protein A canbe used to purify antibodies that are based on human γ1, γ2, or γ4 heavychains (Lindmark et al., J. Immunol. Meth. 62:1-13 (1983)). Protein G isrecommended for all mouse isotypes and for human γ3 (Guss et al., EMBOJ. 5:15671575 (1986)). The matrix to which the affinity ligand isattached is most often agarose, but other matrices are available.Mechanically stable matrices such as controlled pore glass orpoly(styrenedivinyl)benzene allow for faster flow rates and shorterprocessing times than can be achieved with agarose. Where the antibodycomprises a C_(H)3 domain, the Bakerbond ABX™resin (J. T. Baker,Phillipsburg, N.J.) is useful for purification. Other techniques forprotein purification such as fractionation on an ion-exchange column,ethanol precipitation, Reverse Phase HPLC, chromatography on silica,chromatography on heparin SEPHAROSE™ chromatography on an anion orcation exchange resin (such as a polyaspartic acid column),chromatofocusing, SDS-PAGE, and ammonium sulfate precipitation are alsoavailable depending on the antibody to be recovered.

Following any preliminary purification step(s), the mixture comprisingthe antibody of interest and contaminants may be subjected to low pHhydrophobic interaction chromatography using an elution buffer at a pHbetween about 2.5-4.5, preferably performed at low salt concentrations(e.g., from about 0-0.25M salt).

In general, various methodologies for preparing antibodies for use inresearch, testing, and clinical are well-established in the art,consistent with the above-described methodologies and/or as deemedappropriate by one skilled in the art for a particular antibody ofinterest.

V. Immunoconjugates

The invention also provides immunoconjugates (interchangeably referredto as “antibody-drug conjugates,” or “ADCs”) comprising any of theanti-Robo4 antibodies of the invention conjugated to one or morecytotoxic agents, such as a chemotherapeutic agent, a drug, a growthinhibitory agent, a toxin (e.g., an enzymatically active toxin ofbacterial, fungal, plant, or animal origin, or fragments thereof), or aradioactive isotope (i.e., a radioconjugate). Conjugates of an antibodyand one or more small molecule toxins, such as a calicheamicin,maytansinoids, a trichothecene, and CC1065, and the derivatives of thesetoxins that have toxin activity, are also contemplated herein.

In certain embodiments, an immunoconjugate comprises an anti-Robo4antibody and a chemotherapeutic agent or other toxin. Chemotherapeuticagents useful in the generation of immunoconjugates are described herein(e.g., above). Enzymatically active toxins and fragments thereof canalso be used and are described herein.

In certain embodiments, an immunoconjugate comprises an anti-Robo4antibody and one or more small molecule toxins, including, but notlimited to, small molecule drugs such as a calicheamicin, maytansinoid,dolastatin, auristatin, trichothecene, and CC1065, and the derivativesof these drugs that have cytotoxic activity. Examples of suchimmunoconjugates are discussed in further detail below.

A. Exemplary Immunoconjugates

An immunoconjugate (or “antibody-drug conjugate” (“ADC”)) of theinvention may be of Formula I, below, wherein an anti-Robo4 antibody isconjugated (i.e., covalently attached) to one or more drug moieties (D)through an optional linker (L).

Ab-(L-D)_(p)  Formula I

Accordingly, the anti-Robo4 antibody may be conjugated to the drugeither directly or via a linker. In Formula I, p is the average numberof drug moieties per antibody, which can range, e.g., from about 1 toabout 20 drug moieties per antibody, and in certain embodiments, from 1to about 8 drug moieties per antibody.

B. Exemplary Linkers

Exemplary linkers and drug moieties are disclosed herein and in U.S.Patent Publication Nos. 20050238649 A1; 20050276812 A1; and 20070092940A1. A linker may comprise one or more linker components. Exemplarylinker components include 6-maleimidocaproyl (“MC”), maleimidopropanoyl(“MP”), valine-citrulline (“val-cit” or “vc”), alanine-phenylalanine(“ala-phe”), p-aminobenzyloxycarbonyl (a “PAB”), N-Succinimidyl4-(2-pyridylthio) pentanoate (“SPP”), N-succinimidyl4-(N-maleimidomethyl)cyclohexane-1 carboxylate (“SMCC”), andN-Succinimidyl (4-iodo-acetyl)aminobenzoate (“SIAB”), N-succinimidyl3-(2-pyridyldithio) propionate (SPDP) (see, e.g., Carlsson et al.,Biochem. J., 173, 723-737 (1978)), N-succinimidyl 4-(2-pyridyldithio)butanoate (SPDB) (see, e.g., U.S. Pat. No. 4,563,304), N-succinimidyl4-methyl-4-[2-(5-nitro-pyridyl)-dithio]pentanoate (SMNP), and thepolyethylene glycol derivative, methoxy-polyethylene oxide (mPEO).Various linker components are known in the art, some of which aredescribed below.

A linker may be a “cleavable linker,” facilitating release of a drug inthe cell. For example, an acid-labile linker (e.g., hydrazone),protease-sensitive (e.g., peptidase-sensitive) linker, photolabilelinker, dimethyl linker or disulfide-containing linker (Chari et al.,Cancer Research 52:127-131 (1992); U.S. Pat. No. 5,208,020) may be used.

In some embodiments, a linker component may comprise a “stretcher unit”that links an antibody to another linker component or to a drug moiety.Exemplary stretcher units are shown below (wherein the wavy lineindicates sites of covalent attachment to an antibody, another linkercomponent or a drug moiety):

In some embodiments, a linker component may comprise an amino acid unit.In one such embodiment, the amino acid unit allows for cleavage of thelinker by a protease, thereby facilitating release of the drug from theimmunoconjugate upon exposure to intracellular proteases, such aslysosomal enzymes. See, e.g., Doronina et al. (2003). Nat. Biotechnol.21:778-784. Exemplary amino acid units include, but are not limited to,a dipeptide, a tripeptide, a tetrapeptide, and a pentapeptide. Exemplarydipeptides include: valine-citrulline (vc or val-cit),alanine-phenylalanine (af or ala-phe); phenylalanine-lysine (fk orphe-lys); or N-methyl-valine-citrulline (Me-val-cit). Exemplarytripeptides include: glycine-valine-citrulline (gly-val-cit) andglycine-glycine-glycine (gly-gly-gly). An amino acid unit may compriseamino acid residues that occur naturally, as well as minor amino acidsand non-naturally occurring amino acid analogs, such as citrulline.Amino acid units can be designed and optimized in their selectivity forenzymatic cleavage by a particular enzyme, for example, atumor-associated protease, cathepsin B, C and D, or a plasmin protease.

In some embodiments, a linker component may comprise a “spacer” unitthat links the antibody to a drug moiety, either directly or by way of astretcher unit and/or an amino acid unit. A spacer unit may be“self-immolative” or a “non-self-immolative.” A “non-self-immolative”spacer unit is one in which part or all of the spacer unit remains boundto the drug moiety upon enzymatic (e.g., proteolytic) cleavage of theADC. Examples of non-self-immolative spacer units include, but are notlimited to, a glycine spacer unit and a glycine-glycine spacer unit.Other combinations of peptidic spacers susceptible to sequence-specificenzymatic cleavage are also contemplated. For example, enzymaticcleavage of an ADC containing a glycine-glycine spacer unit by atumor-cell associated protease would result in release of aglycine-glycine-drug moiety from the remainder of the ADC. In one suchembodiment, the glycine-glycine-drug moiety is then subjected to aseparate hydrolysis step in the tumor cell, thus cleaving theglycine-glycine spacer unit from the drug moiety.

A “self-immolative” spacer unit allows for release of the drug moietywithout a separate hydrolysis step. In certain embodiments, a spacerunit of a linker comprises a p-aminobenzyl unit. In one such embodiment,a p-aminobenzyl alcohol is attached to an amino acid unit via an amidebond, and a carbamate, methylcarbamate, or carbonate is made between thebenzyl alcohol and a cytotoxic agent. See, e.g., Hamann et al. (2005)Expert Opin. Ther. Patents (2005) 15:1087-1103. In one embodiment, thespacer unit is p-aminobenzyloxycarbonyl (PAB). In certain embodiments,the phenylene portion of a p-amino benzyl unit is substituted with Qm,wherein Q is —C₁-C₈ alkyl, —O—(C₁-C₈ alkyl), -halogen, -nitro or -cyano;and m is an integer ranging from 0-4. Examples of self-immolative spacerunits further include, but are not limited to, aromatic compounds thatare electronically similar to p-aminobenzyl alcohol (see, e.g., US2005/0256030 A1), such as 2-aminoimidazol-5-methanol derivatives (Hay etal. (1999) Bioorg. Med. Chem. Lett. 9:2237) and ortho- orpara-aminobenzylacetals. Spacers can be used that undergo cyclizationupon amide bond hydrolysis, such as substituted and unsubstituted4-aminobutyric acid amides (Rodrigues et al., Chemistry Biology, 1995,2, 223); appropriately substituted bicyclo[2.2.1] and bicyclo[2.2.2]ring systems (Storm, et al., J. Amer. Chem. Soc., 1972, 94, 5815); and2-aminophenylpropionic acid amides (Amsberry, et al., J. Org. Chem.,1990, 55, 5867). Elimination of amine-containing drugs that aresubstituted at the a-position of glycine (Kingsbury, et al., J. Med.Chem., 1984, 27, 1447) are also examples of self-immolative spacersuseful in ADCs.

In one embodiment, a spacer unit is a branched bis(hydroxymethyl)styrene(BHMS) unit as depicted below, which can be used to incorporate andrelease multiple drugs.

wherein Q is —C₁-C₈ alkyl, —O—(C₁-C₈ alkyl), -halogen, -nitro or -cyano;m is an integer ranging from 0-4; n is 0 or 1; and p ranges raging from1 to about 20.

A linker may comprise any one or more of the above linker components. Incertain embodiments, a linker is as shown in brackets in the followingADC Formula II

Ab-([Aa-Ww-Yy]-D)_(p)  Formula II

wherein A is a stretcher unit, and a is an integer from 0 to 1; W is anamino acid unit, and w is an integer from 0 to 12; Y is a spacer unit,and y is 0, 1, or 2; and Ab, D, and p are defined as above for FormulaI. Exemplary embodiments of such linkers are described in US 20050238649A1, which is expressly incorporated herein by reference.

Exemplary linker components and combinations thereof are shown below inthe context of ADCs of Formula II:

Linkers components, including stretcher, spacer, and amino acid units,may be synthesized by methods known in the art, such as those describedin US 2005-0238649 A1.

C. Exemplary Drug Moieties

1. Maytansine and Maytansinoids

In some embodiments, an immunoconjugate comprises an antibody of theinvention conjugated to one or more maytansinoid molecules.Maytansinoids are mitototic inhibitors which act by inhibiting tubulinpolymerization. Maytansine was first isolated from the east Africanshrub Maytenus serrata (U.S. Pat. No. 3,896,111). Subsequently, it wasdiscovered that certain microbes also produce maytansinoids, such asmaytansinol and C-3 maytansinol esters (U.S. Pat. No. 4,151,042).Synthetic maytansinol and derivatives and analogues thereof aredisclosed, for example, in U.S. Pat. Nos. 4,137,230; 4,248,870;4,256,746; 4,260,608; 4,265,814; 4,294,757; 4,307,016; 4,308,268;4,308,269; 4,309,428; 4,313,946; 4,315,929; 4,317,821; 4,322,348;4,331,598; 4,361,650; 4,364,866; 4,424,219; 4,450,254; 4,362,663; and4,371,533, the disclosures of which are hereby expressly incorporated byreference.

Maytansine compounds inhibit cell proliferation by inhibiting theformation of microtubules during mitosis through inhibition ofpolymerization of the microtubulin protein, tubulin (Remillard et al.(1975) Science 189:1002-1005; U.S. Pat. No. 5,208,020). Maytansine andmaytansinoids are highly cytotoxic but their clinical use in cancertherapy has been greatly limited by their severe systemic side-effectsprimarily attributed to their poor selectivity for tumors. Clinicaltrials with maytansine had been discontinued due to serious adverseeffects on the central nervous system and gastrointestinal system (Isselet al., (1978) Can. Treatment. Rev. 5:199-207).

Maytansinoid drug moieties are attractive drug moieties in antibody-drugconjugates because they are: (i) relatively accessible to prepare byfermentation or chemical modification or derivatization of fermentationproducts, (ii) amenable to derivatization with functional groupssuitable for conjugation through non-disulfide linkers to antibodies,(iii) stable in plasma, and (iv) effective against a variety of tumorcell lines.

Maytansine compounds suitable for use as maytansinoid drug moieties arewell known in the art and can be isolated from natural sources accordingto known methods or produced using genetic engineering techniques (seeYu et al. (2002) PNAS 99:7968-7973). Maytansinol and maytansinolanalogues may also be prepared synthetically according to known methods.Exemplary embodiments of maytansinoid drug moieties include: DM1; DM3;and DM4, as disclosed herein below.

As with other drug moieties, all stereoisomers of the maytansinoid drugmoiety are contemplated for the compounds of the invention, i.e. anycombination of R and S configurations at the chiral carbons of D. In oneembodiment, the maytansinoid drug moiety (D) will have the followingstereochemistry:

Exemplary embodiments of maytansinoid drug moieties include: DM1,(CR₂)_(m)═CH₂CH₂; DM3, (CR₂)_(m)═CH₂CH₂CH(CH₃); and DM4,(CR₂)_(m)═CH₂CH₂C(CH₃)₂, having the structures:

In an attempt to improve the therapeutic index of targeted antibodies,maytansine and maytansinoids have been conjugated to antibodiesspecifically binding to tumor cell antigens. Immunoconjugates containingmaytansinoids and their therapeutic use are disclosed, for example, inU.S. Pat. Nos. 5,208,020, 5,416,064 and European Patent EP 0 425 235 B1,the disclosures of which are hereby expressly incorporated by reference.Liu et al., PNAS USA 93:8618-8623 (1996) described immunoconjugatescomprising a maytansinoid designated DM1 linked to the monoclonalantibody C242 directed against human colorectal cancer. The conjugatewas found to be highly cytotoxic towards cultured colon cancer cells,and showed antitumor activity in an in vivo tumor growth assay. Chari etal., Cancer Research 52:127-131 (1992) describe immunoconjugates inwhich a maytansinoid was conjugated via a disulfide linker to the murineantibody A7 binding to an antigen on human colon cancer cell lines, orto another murine monoclonal antibody TA.1 that binds the HER-2/neuoncogene. The cytotoxicity of the TA.1-maytansonoid conjugate was testedin vitro on the human breast cancer cell line SK-BR-3, which expresses3×10⁵ HER-2 surface antigens per cell. The drug conjugate achieved adegree of cytotoxicity similar to the free maytansinoid drug, whichcould be increased by increasing the number of maytansinoid moleculesper antibody molecule. The A7-maytansinoid conjugate showed low systemiccytotoxicity in mice.

Antibody-maytansinoid conjugates are prepared by chemically linking anantibody to a maytansinoid molecule without significantly diminishingthe biological activity of either the antibody or the maytansinoidmolecule. An average of 3-4 maytansinoid molecules conjugated perantibody molecule has shown efficacy in enhancing cytotoxicity of targetcells without negatively affecting the function or solubility of theantibody, although even one molecule of toxin/antibody would be expectedto enhance cytotoxicity over the use of naked antibody. Maytansinoidsare well known in the art and can be synthesized by known techniques orisolated from natural sources. Suitable maytansinoids are disclosed, forexample, in U.S. Pat. No. 5,208,020 and in the other patents andnonpatent publications referred to hereinabove. Preferred maytansinoidsare maytansinol and maytansinol analogues modified in the aromatic ringor at other positions of the maytansinol molecule, such as variousmaytansinol esters.

There are many linking groups known in the art for makingantibody-maytansinoid conjugates, including, for example, thosedisclosed in U.S. Pat. No. 5,208,020 or EP Patent 0 425 235 B1, andChari et al., Cancer Research 52:127-131 (1992). The linking groupsinclude disulfide groups, thioether groups, acid labile groups,photolabile groups, peptidase labile groups, or esterase labile groups,as disclosed in the above-identified patents, disulfide and thioethergroups being preferred.

Conjugates of the antibody and maytansinoid may be made using a varietyof bifunctional protein coupling agents such asN-succinimidyl-3-(2-pyridyldithio) propionate (SPDP),succinimidyl-4-(N-maleimidomethyl)cyclohexane-1-carboxylate,iminothiolane (IT), bifunctional derivatives of imidoesters (such asdimethyl adipimidate HCl), active esters (such as disuccinimidylsuberate), aldehydes (such as glutaraldehyde), bis-azido compounds (suchas bis (p-azidobenzoyl) hexanediamine), bis-diazonium derivatives (suchas bis-(p-diazoniumbenzoyl)-ethylenediamine), diisocyanates (such astoluene 2,6-diisocyanate), and bis-active fluorine compounds (such as1,5-difluoro-2,4-dinitrobenzene). Particularly preferred coupling agentsinclude N-succinimidyl-3-(2-pyridyldithio) propionate (SPDP) (Carlssonet al, Biochem. J. 173:723-737 [1978]) andN-succinimidyl-4-(2-pyridylthio)pentanoate (SPP) to provide for adisulfide linkage.

The linker may be attached to the maytansinoid molecule at variouspositions, depending on the type of the link. For example, an esterlinkage may be formed by reaction with a hydroxyl group usingconventional coupling techniques. The reaction may occur at the C-3position having a hydroxyl group, the C-14 position modified withhydroxymethyl, the C-15 position modified with a hydroxyl group, and theC-20 position having a hydroxyl group. In a preferred embodiment, thelinkage is formed at the C-3 position of maytansinol or a maytansinolanalogue.

2. Auristatins, Dolastatins

In some embodiments, an immunoconjugate comprises an antibody of theinvention conjugated to dolastatin or a dolastatin peptidic analog orderivative, e.g., an auristatin (U.S. Pat. Nos. 5,635,483; 5,780,588).Dolastatins and auristatins have been shown to interfere withmicrotubule dynamics, GTP hydrolysis, and nuclear and cellular division(Woyke et al. (2001) Antimicrob. Agents and Chemother. 45(12):3580-3584)and have anticancer (U.S. Pat. No. 5,663,149) and antifungal activity(Pettit et al. (1998) Antimicrob. Agents Chemother. 42:2961-2965). Thedolastatin or auristatin drug moiety may be attached to the antibodythrough the N (amino) terminus or the C (carboxyl) terminus of thepeptidic drug moiety (WO 02/088172).

Exemplary auristatin embodiments include the N-terminus linkedmonomethylauristatin drug moieties DE and DF, disclosed in Senter et al,Proceedings of the American Association for Cancer Research, Volume 45,Abstract Number 623, presented Mar. 28, 2004, the disclosure of which isexpressly incorporated by reference in its entirety.

A peptidic drug moiety may be selected from Formulas D_(E) and D_(F)below:

-   -   wherein the wavy line of D_(E) and D_(F) indicates the covalent        attachment site to an antibody or antibody-linker component, and        independently at each location:    -   R² is selected from H and C₁-C₈ alkyl;    -   R³ is selected from H, C₁-C₈ alkyl, C₃-C₈ carbocycle, aryl,        C₁-C₈ alkyl-aryl, C₁-C₈ alkyl-(C₃-C₈ carbocycle), C₃-C₈        heterocycle and C₁-C₈ alkyl-(C₃-C₈ heterocycle);    -   R⁴ is selected from H, C₁-C₈ alkyl, C₃-C₈ carbocycle, aryl,        C₁-C₈ alkyl-aryl, C₁-C₈ alkyl-(C₃-C₈ carbocycle), C₃-C₈        heterocycle and C₁-C₈ alkyl-(C₃-C₈ heterocycle);    -   R⁵ is selected from H and methyl;    -   or R⁴ and R⁵ jointly form a carbocyclic ring and have the        formula —(CR^(a)R^(b))_(n)— wherein R^(a) and R^(b) are        independently selected from H, C₁-C₈ alkyl and C₃-C₈ carbocycle        and n is selected from 2, 3, 4, 5 and 6;    -   R⁶ is selected from H and C₁-C₈ alkyl;    -   R⁷ is selected from H, C₁-C₈ alkyl, C₃-C₈ carbocycle, aryl,        C₁-C₈ alkyl-aryl, C₁-C₈ alkyl-(C₃-C₈ carbocycle), C₃-C₈        heterocycle and C₁-C₈ alkyl-(C₃-C₈ heterocycle);    -   each R⁸ is independently selected from H, OH, C₁-C₈ alkyl, C₃-C₈        carbocycle and O—-(C₁-C₈ alkyl);    -   R⁹ is selected from H and C₁-C₈ alkyl;    -   R¹⁰ is selected from aryl or C₃-C₈ heterocycle;    -   Z is O, S, NH, or NR, wherein R¹² is C₁-C₈ alkyl;    -   R¹¹ is selected from H, C₁-C₂₀ alkyl, aryl, C₃-C₈ heterocycle,        —(R¹³O)_(m)—R¹⁴, or —(R¹³O)_(m)—CH(R¹⁵)₂;    -   m is an integer ranging from 1-1000;    -   R¹³ is C₂-C₈ alkyl;    -   R¹⁴ is H or C₁-C₈ alkyl;    -   each occurrence of R¹⁵ is independently H, COOH,        —(CH₂)_(n)—N(R¹⁶)₂, —(CH₂)_(n)—SO₃H, or —(CH₂)_(n)—SO₃—C₁-C₈        alkyl;    -   each occurrence of R¹⁶ is independently H, C₁-C₈ alkyl, or        —(CH₂)_(n)—COOH;    -   R¹⁸ is selected from —C(R⁸)₂—C(R⁸)₂-aryl, —C(R⁸)₂—C(R⁸)₂—(C₃-C₈        heterocycle), and —C(R⁸)₂—C(R⁸)₂—(C₃-C₈ carbocycle); and    -   n is an integer ranging from 0 to 6.

In one embodiment, R³, R⁴ and R⁷ are independently isopropyl orsec-butyl and R⁵ is —H or methyl. In an exemplary embodiment, R³ and R⁴are each isopropyl, R⁵ is —H, and R⁷ is sec-butyl.

In yet another embodiment, R² and R⁶ are each methyl, and R⁹ is —H.

In still another embodiment, each occurrence of R⁸ is —OCH₃.

In an exemplary embodiment, R³ and R⁴ are each isopropyl, R² and R⁶ areeach methyl, R⁵ is —H, R⁷ is sec-butyl, each occurrence of R⁸ is —OCH₃,and R⁹ is —H.

In one embodiment, Z is —O— or —NH—.

In one embodiment, R¹⁰ is aryl.

In an exemplary embodiment, R¹⁰ is -phenyl.

In an exemplary embodiment, when Z is —O—, R¹¹ is —H, methyl or t-butyl.

In one embodiment, when Z is —NH, R¹¹ is —CH(R¹⁵)₂, wherein R¹⁵ is—(CH₂)_(n)—N(R¹⁶)₂, and R¹⁶ is —C₁-C₈ alkyl or —(CH₂)_(n)—COOH.

In another embodiment, when Z is —NH, R¹¹ is —CH(R¹⁵)₂, wherein R¹⁵ is—(CH₂)_(n)—SO₃H.

An exemplary auristatin embodiment of formula D_(E) is MMAE, wherein thewavy line indicates the covalent attachment to a linker (L) of anantibody-drug conjugate:

An exemplary auristatin embodiment of formula D_(F) is MMAF, wherein thewavy line indicates the covalent attachment to a linker (L) of anantibody-drug conjugate (see US 2005/0238649 and Doronina et al. (2006)Bioconjugate Chem. 17:114-124):

Other drug moieties include the following MMAF derivatives, wherein thewavy line indicates the covalent attachment to a linker (L) of anantibody-drug conjugate:

In one aspect, hydrophilic groups including but not limited to,triethylene glycol esters (TEG), as shown above, can be attached to thedrug moiety at R¹¹. Without being bound by any particular theory, thehydrophilic groups assist in the internalization and non-agglomerationof the drug moiety.

Exemplary embodiments of ADCs of Formula I comprising anauristatin/dolastatin or derivative thereof are described in US2005-0238649 A1 and Doronina et al. (2006) Bioconjugate Chem.17:114-124, which is expressly incorporated herein by reference.Exemplary embodiments of ADCs of Formula I comprising MMAE or MMAF andvarious linker components have the following structures andabbreviations (wherein “Ab” is an antibody; p is 1 to about 8, “Val-Cit”is a valine-citrulline dipeptide; and “S” is a sulfur atom:

Exemplary embodiments of ADCs of Formula I comprising MMAF and variouslinker components further include Ab-MC-PAB-MMAF and Ab-PAB-MMAF.Interestingly, immunoconjugates comprising MMAF attached to an antibodyby a linker that is not proteolytically cleavable have been shown topossess activity comparable to immunoconjugates comprising MMAF attachedto an antibody by a proteolytically cleavable linker. See, Doronina etal. (2006) Bioconjugate Chem. 17:114-124. In such instances, drugrelease is believed to be effected by antibody degradation in the cell.Id.

Typically, peptide-based drug moieties can be prepared by forming apeptide bond between two or more amino acids and/or peptide fragments.Such peptide bonds can be prepared, for example, according to the liquidphase synthesis method (see E. Schroder and K. Lübke, “The Peptides”,volume 1, pp 76-136, 1965, Academic Press) that is well known in thefield of peptide chemistry. Auristatin/dolastatin drug moieties may beprepared according to the methods of: US 2005-0238649 A1; U.S. Pat. No.5,635,483; U.S. Pat. No. 5,780,588; Pettit et al. (1989) J. Am. Chem.Soc. 111:5463-5465; Pettit et al. (1998) Anti-Cancer Drug Design13:243-277; Pettit, G. R., et al. Synthesis, 1996, 719-725; Pettit etal. (1996) J. Chem. Soc. Perkin Trans. 15:859-863; and Doronina (2003)Nat. Biotechnol. 21(7):778-784.

In particular, auristatin/dolastatin drug moieties of formula D_(F),such as MMAF and derivatives thereof, may be prepared using methodsdescribed in US 2005-0238649 A1 and Doronina et al. (2006) BioconjugateChem. 17:114-124. Auristatin/dolastatin drug moieties of formula D_(E),such as MMAE and derivatives thereof, may be prepared using methodsdescribed in Doronina et al. (2003) Nat. Biotech. 21:778-784.Drug-linker moieties MC-MMAF, MC-MMAE, MC-vc-PAB-MMAF, andMC-vc-PAB-MMAE may be conveniently synthesized by routine methods, e.g.,as described in Doronina et al. (2003) Nat. Biotech. 21:778-784, andU.S. Patent Publication No. 20050238649 A1, and then conjugated to anantibody of interest.

3. Calicheamicin

Another immunoconjugate of interest comprises an antibody conjugated toone or more calicheamicin molecules. The calicheamicin family ofantibiotics is capable of producing double-stranded DNA breaks atsub-picomolar concentrations. For the preparation of conjugates of thecalicheamicin family, see U.S. Pat. Nos. 5,712,374, 5,714,586,5,739,116, 5,767,285, 5,770,701, 5,770,710, 5,773,001, 5,877,296 (all toAmerican Cyanamid Company). Structural analogues of calicheamicin whichmay be used include, but are not limited to, γ₁ ^(I), α₂ ^(I), α₃ ^(I),N-acetyl-γ₁ ^(I), PSAG and θ^(I) ₁ (Hinman et al., Cancer Research53:3336-3342 (1993), Lode et al., Cancer Research 58:2925-2928 (1998)and the aforementioned U.S. patents to American Cyanamid). Anotheranti-tumor drug that the antibody can be conjugated is QFA which is anantifolate. Both calicheamicin and QFA have intracellular sites ofaction and do not readily cross the plasma membrane. Therefore, cellularuptake of these agents through antibody mediated internalization greatlyenhances their cytotoxic effects.

4. Other Cytotoxic Agents

Other antitumor agents that can be conjugated to the antibodies of theinvention include BCNU, streptozoicin, vincristine and 5-fluorouracil,the family of agents known collectively LL-E33288 complex described inU.S. Pat. Nos. 5,053,394, 5,770,710, as well as esperamicins (U.S. Pat.No. 5,877,296).

Enzymatically active toxins and fragments thereof which can be usedinclude diphtheria A chain, nonbinding active fragments of diphtheriatoxin, exotoxin A chain (from Pseudomonas aeruginosa), ricin A chain,abrin A chain, modeccin A chain, alpha-sarcin, Aleurites fordiiproteins, dianthin proteins, Phytolaca americana proteins (PAPI, PAPII,and PAP-S), momordica charantia inhibitor, curcin, crotin, sapaonariaofficinalis inhibitor, gelonin, mitogellin, restrictocin, phenomycin,enomycin and the tricothecenes. See, for example, WO 93/21232 publishedOct. 28, 1993.

The present invention further contemplates an immunoconjugate formedbetween an antibody and a compound with nucleolytic activity (e.g., aribonuclease or a DNA endonuclease such as a deoxyribonuclease; DNase).

For selective destruction of the tumor, the antibody may comprise ahighly radioactive atom. A variety of radioactive isotopes are availablefor the production of radioconjugated antibodies. Examples includeAt²¹¹, I¹³¹, I¹²⁵, Y⁹⁰, Re¹⁸⁶, Re¹⁸⁸, Sm¹⁵³, Bi²¹², P³², Pb²¹² andradioactive isotopes of Lu.

The radio- or other labels may be incorporated in the conjugate in knownways. For example, the peptide may be biosynthesized or may besynthesized by chemical amino acid synthesis using suitable amino acidprecursors involving, for example, fluorine-19 in place of hydrogen.Labels such as Tc^(99m) or I¹²³, Re¹⁸⁶, Re¹⁸⁸ and In¹¹¹ can be attachedvia a cysteine residue in the peptide. Yttrium-90 can be attached via alysine residue. The IODOGEN method (Fraker et al. (1978) Biochem.Biophys. Res. Commun. 80: 49-57 can be used to incorporate iodine-123.“Monoclonal Antibodies in Immunoscintigraphy” (Chatal, CRC Press 1989)describes other methods in detail.

Anti-Robo4 antibodies of the invention may be conjugated tonanoparticulate agents which may in turn be conjugated to cytotoxicmoieties. Suitable nanoparticular agents include, but are not limitedto, microbubbles (see Ellegala et al., Circulation 108:336-341 (2003))),also referred to as acoustically active lipospheres (AALs) (see Tartiset al., Ultrasound Med. Biol. 32(11):1771-80 (2006)), superparamagneticagents, liposomes, perfluorocarbon nanoparticle emulsions(WO2005014051), and dendrimers (see Caruthers et al., Methods inMolecular Medicine, 124:387-400 (2006) and references cited therein, allof which references are hereby incorporated by reference in theirentirety).

Conjugates of the antibody and cytotoxic agent may be made using avariety of bifunctional protein coupling agents such asN-succinimidyl-3-(2-pyridyldithio) propionate (SPDP),succinimidyl-4-(N-maleimidomethyl)cyclohexane-1-carboxylate,iminothiolane (IT), bifunctional derivatives of imidoesters (such asdimethyl adipimidate HCl), active esters (such as disuccinimidylsuberate), aldehydes (such as glutaraldehyde), bis-azido compounds (suchas bis (p-azidobenzoyl) hexanediamine), bis-diazonium derivatives (suchas bis-(p-diazoniumbenzoyl)-ethylenediamine), diisocyanates (such astoluene 2,6-diisocyanate), and bis-active fluorine compounds (such as1,5-difluoro-2,4-dinitrobenzene). For example, a ricin immunotoxin canbe prepared as described in Vitetta et al., Science 238:1098 (1987).Carbon-14-labeled 1-isothiocyanatobenzyl-3-methyldiethylenetriaminepentaacetic acid (MX-DTPA) is an exemplary chelating agent forconjugation of radionucleotide to the antibody. See WO94/11026. Thelinker may be a “cleavable linker” facilitating release of the cytotoxicdrug in the cell. For example, an acid-labile linker,peptidase-sensitive linker, photolabile linker, dimethyl linker ordisulfide-containing linker (Chari et al., Cancer Research 52:127-131(1992); U.S. Pat. No. 5,208,020) may be used.

The compounds of the invention expressly contemplate, but are notlimited to, ADC prepared with cross-linker reagents: BMPS, EMCS, GMBS,HBVS, LC-SMCC, MBS, MPBH, SBAP, SIA, SIAB, SMCC, SMPB, SMPH, sulfo-EMCS,sulfo-GMBS, sulfo-KMUS, sulfo-MBS, sulfo-SIAB, sulfo-SMCC, andsulfo-SMPB, and SVSB (succinimidyl-(4-vinylsulfone)benzoate) which arecommercially available (e.g., from Pierce Biotechnology, Inc., Rockford,Ill., U.S.A). See pages 467-498, 2003-2004 Applications Handbook andCatalog.

5. Drug Loading

Drug loading is represented by p and is the average number of drugmoieties per antibody in a molecule of Formula I, Ia, Ia′ or II. Drugloading may range from 1 to 20 drug moieties (D) per antibody. ADCs ofFormula I include collections of antibodies conjugated with a range ofdrug moieties, from 1 to 20. The average number of drug moieties perantibody in preparations of ADC from conjugation reactions may becharacterized by conventional means such as mass spectroscopy, ELISAassay, and HPLC. The quantitative distribution of ADC in terms of p mayalso be determined. In some instances, separation, purification, andcharacterization of homogeneous ADC where p is a certain value from ADCwith other drug loadings may be achieved by means such as reverse phaseHPLC or electrophoresis.

For some antibody-drug conjugates, p may be limited by the number ofattachment sites on the antibody. For example, where the attachment is acysteine thiol, as in the exemplary embodiments above, an antibody mayhave only one or several cysteine thiol groups, or may have only one orseveral sufficiently reactive thiol groups through which a linker may beattached. In certain embodiments, higher drug loading, e.g. p>5, maycause aggregation, insolubility, toxicity, or loss of cellularpermeability of certain antibody-drug conjugates. In certainembodiments, the drug loading for an ADC of the invention ranges from 1to about 8; from about 2 to about 6; from about 3 to about 5; from about3 to about 4; from about 3.1 to about 3.9; from about 3.2 to about 3.8;from about 3.2 to about 3.7; from about 3.2 to about 3.6; from about 3.3to about 3.8; or from about 3.3 to about 3.7. Indeed, it has been shownthat for certain ADCs, the optimal ratio of drug moieties per antibodymay be less than 8, and may be about 2 to about 5. See US 2005-0238649A1 (herein incorporated by reference in its entirety).

In certain embodiments, fewer than the theoretical maximum of drugmoieties are conjugated to an antibody during a conjugation reaction. Anantibody may contain, for example, lysine residues that do not reactwith the drug-linker intermediate or linker reagent, as discussed below.Generally, antibodies do not contain many free and reactive cysteinethiol groups which may be linked to a drug moiety; indeed most cysteinethiol residues in antibodies exist as disulfide bridges. In certainembodiments, an antibody may be reduced with a reducing agent such asdithiothreitol (DTT) or tricarbonylethylphosphine (TCEP), under partialor total reducing conditions, to generate reactive cysteine thiolgroups. In certain embodiments, an antibody is subjected to denaturingconditions to reveal reactive nucleophilic groups such as lysine orcysteine.

The loading (drug/antibody ratio) of an ADC may be controlled indifferent ways, e.g., by: (i) limiting the molar excess of drug-linkerintermediate or linker reagent relative to antibody, (ii) limiting theconjugation reaction time or temperature, (iii) partial or limitingreductive conditions for cysteine thiol modification, (iv) engineeringby recombinant techniques the amino acid sequence of the antibody suchthat the number and position of cysteine residues is modified forcontrol of the number and/or position of linker-drug attachements (suchas thioMab or thioFab prepared as disclosed herein and in WO2006/034488(herein incorporated by reference in its entirety)). In an embodiment ofthe invention, an amino acid residue of the antibody of the invention issubstituted with a cysteine residue. In an embodiment, the amino acid atposition 118 of the heavy chain Fc region of the antibody is a cysteineor is substituted with a cysteine residue (where 118 refers to the aminoacid position in the Fc region of the antibody numbered according to EUnumbering, see Kabat, E. A. et al., Sequences of Proteins ofImmunological Interest (U.S. Dept. of Health and Hum. Serv., Bethesda(1991)). In an embodiment, the cysteine residue at position 118 of theheavy chain Fc region (EU numbering) is covalently attached to a drugmoiety or a detectable label, such as the drug moieties or detectablelabels disclosed herein. In FIG. 6A, the alanine of the heavy chain Fcregion shown in bold text and underlined is the position at which acysteine was substituted to generate the thioMAb.

It is to be understood that where more than one nucleophilic groupreacts with a drug-linker intermediate or linker reagent followed bydrug moiety reagent, then the resulting product is a mixture of ADCcompounds with a distribution of one or more drug moieties attached toan antibody. The average number of drugs per antibody may be calculatedfrom the mixture by a dual ELISA antibody assay, which is specific forantibody and specific for the drug. Individual ADC molecules may beidentified in the mixture by mass spectroscopy and separated by HPLC,e.g. hydrophobic interaction chromatography (see, e.g., Hamblett, K. J.,et al. “Effect of drug loading on the pharmacology, pharmacokinetics,and toxicity of an anti-CD30 antibody-drug conjugate,” Abstract No. 624,American Association for Cancer Research, 2004 Annual Meeting, Mar.27-31, 2004, Proceedings of the AACR, Volume 45, March 2004; Alley, S.C., et al. “Controlling the location of drug attachment in antibody-drugconjugates,” Abstract No. 627, American Association for Cancer Research,2004 Annual Meeting, Mar. 27-31, 2004, Proceedings of the AACR, Volume45, March 2004). In certain embodiments, a homogeneous ADC with a singleloading value may be isolated from the conjugation mixture byelectrophoresis or chromatography.

D. Metabolites of the Antibody-Drug Conjugates

Also falling within the scope of this invention are the in vivometabolic products of the ADC compounds described herein, to the extentsuch products are novel and unobvious over the prior art. Such productsmay result for example from the oxidation, reduction, hydrolysis,amidation, esterification, enzymatic cleavage, and the like, of theadministered compound. Accordingly, the invention includes novel andunobvious compounds produced by a process comprising contacting acompound of this invention with a mammal for a period of time sufficientto yield a metabolic product thereof.

Metabolite products typically are identified by preparing a radiolabeled(e.g. ¹⁴C or ³H) ADC, administering it parenterally in a detectable dose(e.g. greater than about 0.5 mg/kg) to an animal such as rat, mouse,guinea pig, monkey, or to man, allowing sufficient time for metabolismto occur (typically about 30 seconds to 30 hours) and isolating itsconversion products from the urine, blood or other biological samples.These products are easily isolated since they are labeled (others areisolated by the use of antibodies capable of binding epitopes survivingin the metabolite). The metabolite structures are determined inconventional fashion, e.g. by MS, LC/MS or NMR analysis. In general,analysis of metabolites is done in the same way as conventional drugmetabolism studies well-known to those skilled in the art. Theconversion products, so long as they are not otherwise found in vivo,are useful in diagnostic assays for therapeutic dosing of the ADCcompounds of the invention.

VI. Methods of Preparing Immunconjugates

In the antibody drug conjugates (ADC) of the invention, an antibody (Ab)is conjugated to one or more drug moieties (D), e.g. about 1 to about 20drug moieties per antibody, through a linker (L). An ADC of Formula I,Ia, Ia′, or II may be prepared by several routes employing organicchemistry reactions, conditions, and reagents known to those skilled inthe art, including: (1) reaction of a nucleophilic group of an antibodywith a bivalent linker reagent to form Ab-L via a covalent bond,followed by reaction with a drug moiety D; and (2) reaction of anucleophilic group of a drug moiety with a bivalent linker reagent, toform D-L, via a covalent bond, followed by reaction with a nucleophilicgroup of an antibody. Exemplary methods for preparing an ADC of FormulaI via the latter route are described in U.S. Patent Publication No.20050238649 A1, which is expressly incorporated herein by reference.

Nucleophilic groups on antibodies include, but are not limited to: (i)N-terminal amine groups, (ii) side chain amine groups, e.g. lysine,(iii) side chain thiol groups, e.g. cysteine, and (iv) sugar hydroxyl oramino groups where the antibody is glycosylated. Amine, thiol, andhydroxyl groups are nucleophilic and capable of reacting to formcovalent bonds with electrophilic groups on linker moieties and linkerreagents including: (i) active esters such as NHS esters, HOBt esters,haloformates, and acid halides; (ii) alkyl and benzyl halides such ashaloacetamides; (iii) aldehydes, ketones, carboxyl, and maleimidegroups. Certain antibodies have reducible interchain disulfides, i.e.cysteine bridges. Antibodies may be made reactive for conjugation withlinker reagents by treatment with a reducing agent such as DTT(dithiothreitol) or tricarbonylethylphosphine (TCEP), such that theantibody is fully or partially reduced. Each cysteine bridge will thusform, theoretically, two reactive thiol nucleophiles. Additionalnucleophilic groups can be introduced into antibodies throughmodification of lysine residues, e.g., by reacting lysine residues with2-iminothiolane (Traut's reagent), resulting in conversion of an amineinto a thiol. Reactive thiol groups may be introduced into an antibodyby introducing one, two, three, four, or more cysteine residues (e.g.,by preparing variant antibodies comprising one or more non-nativecysteine amino acid residues).

Antibody-drug conjugates of the invention may also be produced byreaction between an electrophilic group on an antibody, such as analdehyde or ketone carbonyl group, with a nucleophilic group on a linkerreagent or drug. Useful nucleophilic groups on a linker reagent include,but are not limited to, hydrazide, oxime, amino, hydrazine,thiosemicarbazone, hydrazine carboxylate, and arylhydrazide. In oneembodiment, an antibody is modified to introduce electrophilic moietiesthat are capable of reacting with nucleophilic substituents on thelinker reagent or drug. In another embodiment, the sugars ofglycosylated antibodies may be oxidized, e.g. with periodate oxidizingreagents, to form aldehyde or ketone groups which may react with theamine group of linker reagents or drug moieties. The resulting imineSchiff base groups may form a stable linkage, or may be reduced, e.g. byborohydride reagents to form stable amine linkages. In one embodiment,reaction of the carbohydrate portion of a glycosylated antibody witheither galactose oxidase or sodium meta-periodate may yield carbonyl(aldehyde and ketone) groups in the antibody that can react withappropriate groups on the drug (Hermanson, Bioconjugate Techniques). Inanother embodiment, antibodies containing N-terminal serine or threonineresidues can react with sodium meta-periodate, resulting in productionof an aldehyde in place of the first amino acid (Geoghegan & Stroh,(1992) Bioconjugate Chem. 3:138-146; U.S. Pat. No. 5,362,852). Such analdehyde can be reacted with a drug moiety or linker nucleophile.

Nucleophilic groups on a drug moiety include, but are not limited to:amine, thiol, hydroxyl, hydrazide, oxime, hydrazine, thiosemicarbazone,hydrazine carboxylate, and arylhydrazide groups capable of reacting toform covalent bonds with electrophilic groups on linker moieties andlinker reagents including: (i) active esters such as NHS esters, HOBtesters, haloformates, and acid halides; (ii) alkyl and benzyl halidessuch as haloacetamides; (iii) aldehydes, ketones, carboxyl, andmaleimide groups.

The compounds of the invention expressly contemplate, but are notlimited to, ADC prepared with the following cross-linker reagents: BMPS,EMCS, GMBS, HBVS, LC-SMCC, MBS, MPBH, SBAP, SIA, SIAB, SMCC, SMPB, SMPH,sulfo-EMCS, sulfo-GMBS, sulfo-KMUS, sulfo-MBS, sulfo-SIAB, sulfo-SMCC,and sulfo-SMPB, and SVSB (succinimidyl-(4-vinylsulfone)benzoate) whichare commercially available (e.g., from Pierce Biotechnology, Inc.,Rockford, Ill., U.S.A; see pages 467-498, 2003-2004 ApplicationsHandbook and Catalog.

Immunoconjugates comprising an antibody and a cytotoxic agent may alsobe made using a variety of bifunctional protein coupling agents such asN-succinimidyl-3-(2-pyridyldithio) propionate (SPDP),succinimidyl-4-(N-maleimidomethyl)cyclohexane-1-carboxylate (SMCC),iminothiolane (IT), bifunctional derivatives of imidoesters (such asdimethyl adipimidate HCl), active esters (such as disuccinimidylsuberate), aldehydes (such as glutaraldehyde), bis-azido compounds (suchas bis (p-azidobenzoyl) hexanediamine), bis-diazonium derivatives (suchas bis-(p-diazoniumbenzoyl)-ethylenediamine), diisocyanates (such astoluene 2,6-diisocyanate), and bis-active fluorine compounds (such as1,5-difluoro-2,4-dinitrobenzene). For example, a ricin immunotoxin canbe prepared as described in Vitetta et al., Science 238:1098 (1987).Carbon-14-labeled 1-isothiocyanatobenzyl-3-methyldiethylenetriaminepentaacetic acid (MX-DTPA) is an exemplary chelating agent forconjugation of radionucleotide to the antibody. See WO94/11026.

Alternatively, a fusion protein comprising an antibody and a cytotoxicagent may be made, e.g., by recombinant techniques or peptide synthesis.A recombinant DNA molecule may comprise regions encoding the antibodyand cytotoxic portions of the conjugate either adjacent to one anotheror separated by a region encoding a linker peptide which does notdestroy the desired properties of the conjugate.

The compounds of the invention include cysteine engineered antibodieswhere one or more amino acids of a parent antibody are replaced with afree cysteine amino acid. A cysteine engineered antibody comprises oneor more free cysteine amino acids having a thiol reactivity value in therange of 0.6 to 1.0. A free cysteine amino acid is a cysteine residuewhich has been engineered into the parent antibody and is not part of adisulfide bridge.

In one aspect, the cysteine engineered antibody is prepared by a processcomprising:

(a) replacing one or more amino acid residues of a parent antibody bycysteine; and(b) determining the thiol reactivity of the cysteine engineered antibodyby reacting the cysteine engineered antibody with a thiol-reactivereagent.The cysteine engineered antibody may be more reactive than the parentantibody with the thiol-reactive reagent.

The free cysteine amino acid residues may be located in the heavy orlight chains, or in the constant or variable domains. Antibodyfragments, e.g. Fab, may also be engineered with one or more cysteineamino acids replacing amino acids of the antibody fragment, to formcysteine engineered antibody fragments.

Another aspect of the invention provides a method of preparing (making)a cysteine engineered antibody, comprising:

(a) introducing one or more cysteine amino acids into a parent antibodyin order to generate the cysteine engineered antibody; and

(b) determining the thiol reactivity of the cysteine engineered antibodywith a thiol-reactive reagent;

wherein the cysteine engineered antibody is more reactive than theparent antibody with the thiol-reactive reagent.

Step (a) of the method of preparing a cysteine engineered antibody maycomprise:

(i) mutagenizing a nucleic acid sequence encoding the cysteineengineered antibody;

(ii) expressing the cysteine engineered antibody; and

(iii) isolating and purifying the cysteine engineered antibody.

Step (b) of the method of preparing a cysteine engineered antibody maycomprise expressing the cysteine engineered antibody on a viral particleselected from a phage or a phagemid particle.

Step (b) of the method of preparing a cysteine engineered antibody mayalso comprise:

(i) reacting the cysteine engineered antibody with a thiol-reactiveaffinity reagent to generate an affinity labeled, cysteine engineeredantibody; and

(ii) measuring the binding of the affinity labeled, cysteine engineeredantibody to a capture media.

Another aspect of the invention is a method of screening cysteineengineered antibodies with highly reactive, unpaired cysteine aminoacids for thiol reactivity comprising:

(a) introducing one or more cysteine amino acids into a parent antibodyin order to generate a cysteine engineered antibody;

(b) reacting the cysteine engineered antibody with a thiol-reactiveaffinity reagent to generate an affinity labeled, cysteine engineeredantibody; and

(c) measuring the binding of the affinity labeled, cysteine engineeredantibody to a capture media; and

(d) determining the thiol reactivity of the cysteine engineered antibodywith the thiol-reactive reagent.

Step (a) of the method of screening cysteine engineered antibodies maycomprise:

(i) mutagenizing a nucleic acid sequence encoding the cysteineengineered antibody;

(ii) expressing the cysteine engineered antibody; and

(iii) isolating and purifying the cysteine engineered antibody.

Step (b) of the method of screening cysteine engineered antibodies maycomprise expressing the cysteine engineered antibody on a viral particleselected from a phage or a phagemid particle.

Step (b) of the method of screening cysteine engineered antibodies mayalso comprise:

(i) reacting the cysteine engineered antibody with a thiol-reactiveaffinity reagent to generate an affinity labeled, cysteine engineeredantibody; and

(ii) measuring the binding of the affinity labeled, cysteine engineeredantibody to a capture media.

Cysteine engineered antibodies may be useful in the treatment of cancerand include antibodies specific for cell surface and transmembranereceptors, and tumor-associated antigens (TAA). Such antibodies may beused as naked antibodies (unconjugated to a drug or label moiety) or asFormula I, Ia, Ia′ or II antibody-drug conjugates (ADC).

Embodiments of the methods for preparing and screening a cysteineengineered antibody include where the parent antibody is an antibodyfragment, such as hu4D5Fabv8. The parent antibody may also be a fusionprotein comprising an albumin-binding peptide sequence (ABP).

Cysteine engineered antibodies of the invention may be site-specificallyand efficiently coupled with a thiol-reactive reagent. Thethiol-reactive reagent may be a multifunctional linker reagent, acapture label reagent, a fluorophore reagent, or a drug-linkerintermediate.

The cysteine engineered antibody may be labeled with a detectable label,immobilized on a solid phase support and/or conjugated with a drugmoiety.

Another aspect of the invention is an antibody-drug conjugate compoundcomprising a cysteine engineered antibody (Ab), and a drug moiety (D)wherein the cysteine engineered antibody is attached through one or morefree cysteine amino acids by a linker moiety (L) to D; the compoundhaving Formula Ia:

Ab(LD)_(p)  Ia

where p is 1, 2, 3, or 4; and wherein the cysteine engineered antibodyis prepared by a process comprising replacing one or more amino acidresidues of a parent antibody by one or more free cysteine amino acids.Drug moieties include, but are not limited to a maytansinoid, anauristatin, a dolastatin, a trichothecene, CC1065, a calicheamicin andother enediyne antibiotics, a taxane, an anthracycline, andstereoisomers, isosteres, analogs or derivatives thereof. Exemplary drugmoieties include DM1, MMAE, and MMAF. Exemplary antibody-drug conjugatesare set forth in U.S. Patent Publication No. 20070092940 A1.

The antibody-drug conjugate of Formula Ia may further comprise analbumin-binding peptide (ABP) sequence; the composition having FormulaIa′:

ABPAb(LD)_(p)  Ia′

Antibodies of the invention comprising fusion proteins with ABPsequences are taught by: (i) Dennis et al. (2002) J Biol. Chem.277:35035-35043 at Tables III and IV, page 35038; (ii) US 20040001827 at[0076] SEQ ID NOS: 9-22; and (iii) WO 01/45746 at pages 12-13, SEQ IDNOS: z1-z14, and all of which are incorporated herein by reference.

VII. Cysteine Engineered Antibodies (ThioMAbs and ThioFabs)

The compounds of the invention include cysteine engineered antibodieswhere one or more amino acids of a wild-type or parent antibody arereplaced with a cysteine amino acid. Any form of antibody may be soengineered, i.e. mutated. For example, a parent Fab antibody fragmentmay be engineered to form a cysteine engineered Fab, referred to hereinas “ThioFab.” Similarly, a parent monoclonal antibody may be engineeredto form a “ThioMab.” It should be noted that a single site mutationyields a single engineered cysteine residue in a ThioFab, while a singlesite mutation yields two engineered cysteine residues in a ThioMab, dueto the dimeric nature of the IgG antibody. Mutants with replaced(“engineered”) cysteine (Cys) residues are evaluated for the reactivityof the newly introduced, engineered cysteine thiol groups. The thiolreactivity value is a relative, numerical term in the range of 0 to 1.0and can be measured for any cysteine engineered antibody. Thiolreactivity values of cysteine engineered antibodies of the invention arein the ranges of 0.6 to 1.0; 0.7 to 1.0; or 0.8 to 1.0.

The design, selection, and preparation methods of the invention enablecysteine engineered antibodies which are reactive with electrophilicfunctionality. These methods further enable antibody conjugate compoundssuch as antibody-drug conjugate (ADC) compounds with drug molecules atdesignated, designed, selective sites. Reactive cysteine residues on anantibody surface allow specifically conjugating a drug moiety through athiol reactive group such as maleimide or haloacetyl. The nucleophilicreactivity of the thiol functionality of a Cys residue to a maleimidegroup is about 1000 times higher compared to any other amino acidfunctionality in a protein, such as amino group of lysine residues orthe N-terminal amino group. Thiol specific functionality in iodoacetyland maleimide reagents may react with amine groups, but higher pH (>9.0)and longer reaction times are required (Garman, 1997, Non-RadioactiveLabelling: A Practical Approach, Academic Press, London).

Cysteine engineered antibodies of the invention preferably retain theantigen binding capability of their wild type, parent antibodycounterparts. Thus, cysteine engineered antibodies are capable ofbinding, preferably specifically, to antigens. Such antigens include,for example, tumor-associated antigens (TAA), cell surface receptorproteins and other cell surface molecules, transmembrane proteins,signalling proteins, cell survival regulatory factors, cellproliferation regulatory factors, molecules associated with (for e.g.,known or suspected to contribute functionally to) tissue development ordifferentiation, lymphokines, cytokines, molecules involved in cellcycle regulation, molecules involved in vasculogenesis and moleculesassociated with (for e.g., known or suspected to contribute functionallyto) angiogenesis. The tumor-associated antigen may be a clusterdifferentiation factor (i.e., a CD protein). An antigen to which acysteine engineered antibody is capable of binding may be a member of asubset of one of the above-mentioned categories, wherein the othersubset(s) of said category comprise other molecules/antigens that have adistinct characteristic (with respect to the antigen of interest).

The parent antibody may also be a human or humanized anti-Robo4 antibodyor Fab having any one, two, three, four, five or six of the HVRsequences disclosed herein. Cysteine engineered antibodies of theinvention may be site-specifically and efficiently coupled with athiol-reactive reagent. The thiol-reactive reagent may be amultifunctional linker reagent, a capture, i.e. affinity, label reagent(e.g. a biotin-linker reagent), a detection label (e.g. a fluorophorereagent), a solid phase immobilization reagent (e.g. SEPHAROSE™,polystyrene, or glass), or a drug-linker intermediate. One example of athiol-reactive reagent is N-ethyl maleimide (NEM). In an exemplaryembodiment, reaction of a ThioFab with a biotin-linker reagent providesa biotinylated ThioFab by which the presence and reactivity of theengineered cysteine residue may be detected and measured. Reaction of aThioFab with a multifunctional linker reagent provides a ThioFab with afunctionalized linker which may be further reacted with a drug moietyreagent or other label. Reaction of a ThioFab with a drug-linkerintermediate provides a ThioFab drug conjugate.

Such an approach may be applied to the conjugation of otherthiol-reactive agents in which the reactive group is, for example, amaleimide, an iodoacetamide, a pyridyl disulfide, or otherthiol-reactive conjugation partner (Haugland, 2003, Molecular ProbesHandbook of Fluorescent Probes and Research Chemicals, Molecular Probes,Inc.; Brinkley, 1992, Bioconjugate Chem. 3:2; Garman, 1997,Non-Radioactive Labelling: A Practical Approach, Academic Press, London;Means (1990) Bioconjugate Chem. 1:2; Hermanson, G. in BioconjugateTechniques (1996) Academic Press, San Diego, pp. 40-55, 643-671). Thepartner may be a cytotoxic agent (e.g. a toxin such as doxorubicin orpertussis toxin), a fluorophore such as a fluorescent dye likefluorescein or rhodamine, a chelating agent for an imaging orradiotherapeutic metal, a peptidyl or non-peptidyl label or detectiontag, or a clearance-modifying agent such as various isomers ofpolyethylene glycol, a peptide that binds to a third component, oranother carbohydrate or lipophilic agent.

The sites identified on the exemplary antibody fragment are primarily inthe constant domain of an antibody which is well conserved across allspecies of antibodies. These sites should be broadly applicable to otherantibodies, without further need of structural design or knowledge ofspecific antibody structures, and without interference in the antigenbinding properties inherent to the variable domains of the antibody.

The PHESELECTOR assay (Phage ELISA for Selection of Reactive Thiols,disclosed in WO2006/034488 (herein incorporated by reference in itsentirety)) allows for detection of reactive cysteine groups inantibodies in an ELISA phage format. The process of coating the protein(e.g. antibody) of interest on well surfaces, followed incubation withphage particles and then HRP labeled secondary antibody with absorbancedetection is detailed in WO2006/034488. Mutant proteins displayed onphage may be screened in a rapid, robust, and high-throughput manner.Libraries of cysteine engineered antibodies can be produced andsubjected to binding selection using the same approach to identifyappropriately reactive sites of free Cys incorporation from randomprotein-phage libraries of antibodies or other proteins. This techniqueincludes reacting cysteine mutant proteins displayed on phage with anaffinity reagent or reporter group which is also thiol-reactive.

Cysteine engineered antibodies which may be useful in the treatment ofcancer include, but are not limited to, antibodies against cell surfacereceptors and tumor-associated antigens (TAA). Such antibodies may beused as naked antibodies (unconjugated to a drug or label moiety) or asFormula I, Ia, Ia′, or II antibody-drug conjugates (ADC).Tumor-associated antigens are known in the art, and can prepared for usein generating antibodies using methods and information which are wellknown in the art. In attempts to discover effective cellular targets forcancer diagnosis and therapy, researchers have sought to identifytransmembrane or otherwise tumor-associated polypeptides that arespecifically expressed on the surface of one or more particular type(s)of cancer cell as compared to on one or more normal non-cancerouscell(s) or expressed on the surface of angiogenic cells (such asvascular endothelial cells) as compared to non-endothelial cellsunassociated with cancer. Often, such tumor-associated polypeptides aremore abundantly expressed on the surface of the cancer cells orangiogenic cells as compared to on the surface of the non-cancerouscells or non-angiogenic cells. The identification of suchtumor-associated cell surface antigen polypeptides has given rise to theability to specifically target cancer cells or angiogenic cells fordestruction via antibody-based therapies.

In yet another embodiment, an antibody may be conjugated to a “receptor”(such as streptavidin) for utilization in tumor pre-targeting whereinthe antibody-receptor conjugate is administered to the patient, followedby removal of unbound conjugate from the circulation using a clearingagent and then administration of a “ligand” (e.g., avidin) which isconjugated to a cytotoxic agent (e.g., a radionucleotide).

VIII. Methods of Treatment Using Anti-Robo4 Antibodies

It is contemplated that the anti-Robo4 antibodies (including, e.g.,naked anti-Robo4 antibodies and ADC) of the present invention may beused to treat various diseases or disorders, e.g. characterized by theoverexpression of a tumor or angiogenesis associated antigen such asRobo4. Exemplary conditions of hyperproliferative disorders includepathological conditions associated with abnormal or unwanted endothelialcell proliferation, such as abnormal or unwanted vascular cellproliferation in disorders including, but not limited to, cancer,angiogenesis and disorders associated with (e.g., augmented byendothelial cell proliferation within the tissue experiencing thedisorder) solid tumors and metastasis, atherosclerosis, retrolentalfibroplasia, hemangiomas, chronic inflammation, intraocular neovasculardiseases such as proliferative retinopathies, e.g., diabeticretinopathy, age-related macular degeneration (AMD), neovascularglaucoma, immune rejection of transplanted corneal tissue and othertissues, rheumatoid arthritis, and psoriasis.

The anti-Robo4 antibodies and ADC compounds which are identified inanimal models and cell-based assays can be further tested intumor-bearing higher primates and human clinical trials. Human clinicaltrials can be designed to test the efficacy of the anti-Robo4 monoclonalantibody or immunoconjugate of the invention in patients experiencing acell proliferative disorder including without limitation pathologicalconditions associated with abnormal or unwanted endothelial cellproliferation, such as abnormal or unwanted vascular cell proliferationin disorders including, but not limited to, cancer, angiogenesis anddisorders associated with (e.g., augmented by endothelial cellproliferation within the tissue experiencing the disorder) solid tumorsand metastasis, atherosclerosis, retrolental fibroplasia, hemangiomas,chronic inflammation, intraocular neovascular diseases such asproliferative retinopathies, e.g., diabetic retinopathy, age-relatedmacular degeneration (AMD), neovascular glaucoma, immune rejection oftransplanted corneal tissue and other tissues, rheumatoid arthritis, andpsoriasis. The clinical trial may be designed to evaluate the efficacyof an anti-Robo4 antibody in combinations with known therapeuticregimens, such as radiation and/or chemotherapy involving knownchemotherapeutic and/or cytotoxic agents.

The cancer may comprise Robo4-expressing cells, such that an anti-Robo4antibody of the present invention is able to bind to theRobo4-expressing endothelial cells within the cancer tissue. Todetermine Robo4 expression in the cancer, various diagnostic/prognosticassays are available. In one embodiment, Robo4 overexpression may beanalyzed by IHC. Paraffin-embedded tissue sections from a tumor biopsymay be subjected to the IHC assay and accorded a Robo4 protein stainingintensity criteria with respect to the degree of staining and in whatproportion of tumor cells examined. In one embodiment, Robo4overexpression may be analyzed by detection in vivo or in vitro ofanti-Robo4 antibody labeled with a detectable marker contacted withRobo4-expressing cells in vivo. Detectable markers include withoutlimitation radioisotopes, fluorescent compounds, metallic and/ormagnetic nanoparticles, microbubbles, chelating ligands, and otherdetectable markers as disclosed herein.

For the prevention or treatment of disease, the appropriate dosage of ananti-Robo4 antibody will depend on the type of disease to be treated, asdefined above, the severity and course of the disease, whether themolecule is administered for preventive or therapeutic purposes,previous therapy, the patient's clinical history and response to theantibody, and the discretion of the attending physician. The molecule issuitably administered to the patient at one time or over a series oftreatments. Depending on the type and severity of the disease, about 1μg/kg to 15 mg/kg (e.g. 0.1-20 mg/kg) of molecule is an initialcandidate dosage for administration to the patient, whether, forexample, by one or more separate administrations, or by continuousinfusion. A typical daily dosage might range from about 1 μg/kg to 100mg/kg or more, depending on the factors mentioned above. An exemplarydosage of ADC to be administered to a patient is in the range of about0.1 to about 10 mg/kg of patient weight.

For repeated administrations over several days or longer, depending onthe condition, the treatment is sustained until a desired suppression ofdisease symptoms occurs. An exemplary dosing regimen comprisesadministering an initial loading dose of about 4 mg/kg, followed by aweekly maintenance dose of about 2 mg/kg of an anti-Robo4 antibody.Other dosage regimens may be useful. In yet another embodiment, thedosage range is 275-375 mg/m2 The progress of this therapy is easilymonitored by conventional techniques and assays.

A. Administration of Anti-Robo4 Antibodies

The anti-Robo4 antibodies (and adjunct therapeutic agent) of theinvention may be administered by any route appropriate to the conditionto be treated, including parenteral, subcutaneous, intraperitoneal,intrapulmonary, and intranasal, and, if desired for local treatment,intralesional administration. The anti-Robo4 antibodies will typicallybe administered parenterally, i.e. infusion, subcutaneous,intramuscular, intravenous, intradermal, intrathecal, epidural,intraarterial, and intraperitoneal. In addition, the antibody issuitably administered by pulse infusion, particularly with decliningdoses of the antibody. Dosing can be by any suitable route, e.g. byinjections, such as intravenous or subcutaneous injections, depending inpart on whether the administration is brief or chronic.

For treating cancers or any disease in which angiogenisis occurs, theanti-Robo4 antibody or antibody-drug conjugate is administered viaintravenous infusion. The dosage administered via infusion is in therange of about 1 μg/m² to about 10,000 μg/m² per dose, generally onedose per week for a total of one, two, three or four doses.Alternatively, the dosage range is about 1 μg/m² to about 1000 μg/m²,about 1 μg/m² to about 800 μg/m², about 1 μg/m² to about 600 μg/m²,about 1 μg/m² to about 400 μg/m², about 10 μg/m² to about 500 μg/m²,about 10 μg/m² to about 300 μg/m², about 10 μg/m² to about 200 μg/m², orabout 1 μg/m² to about 200 μg/m². The dose may be administered once perday, once per week, multiple times per week, but less than once per day,multiple times per month but less than once per day, multiple times permonth but less than once per week, once per month or intermittently torelieve or alleviate symptoms of the disease. Administration maycontinue at any of the disclosed intervals until the symptoms of thedisease or disorder being treated are reduced, alleviated, or eliminated(e.g., as indicated by shrinkage of a tumor, reduction of elimination ofsymptoms of lymphoma, leukemia, inhibition of metastatic spread withoutshrinkage of the primary tumor (i.e., progression-free survival),inhibition of ocular neovascularization). Administration may continueafter remission or relief of symptoms is achieved where such remissionor relief is prolonged by such continued administration.

The invention also provides a method of treating a cancer, and/or ametastasis of a cancer and/or an ocular disorder characterized byproliferation of vascular endothelial cells, comprising administering toa patient suffering from such a disorder, a therapeutically effectiveamount of an anti-Robo4 antibody of any one of the precedingembodiments, which antibody is not conjugated to a cytotoxic molecule ora detectable molecule. The antibody will typically be administered in adosage range of about 1 μg/m² to about 1000 mg/m². Alternatively, thedosage range is about 1 μg/m² to about 800 μg/m², about 1 μg/m² to about600 μg/m², about 1 μg/m² to about 400 μg/m², about 10 μg/m² to about 500μg/m², about 10 μg/m² to about 300 μg/m², about 10 μg/m² to about 200μg/m², or about 1 μg/m² to about 200 μg/m².

The invention also provides a method of treating a cancer, and/or ametastasis of a cancer and/or an ocular disorder characterized byproliferation of vascular endothelial cells, comprising administering toa patient suffering from such a disorder, a therapeutically effectiveamount of an anti-Robo4 antibody of any one of the precedingembodiments, which antibody is conjugated to a cytotoxic molecule or adetectable molecule. The antibody will typically be administered in adosage range of about 1 μg/m² to about 1000 mg/m². Alternatively, thedosage range is about 1 μg/m² to about 800 μg/m², about 1 μg/m² to about600 μg/m², about 1 μg/m² to about 400 μg/m², about 10 μg/m² to about 500μg/m², about 10 μg/m² to about 300 μg/m², about 10 μg/m² to about 200μg/m², or about 1 μg/m² to about 200 μg/m².

B. Pharmaceutical Formulations

In one aspect, the invention further provides pharmaceuticalformulations comprising at least one anti-Robo4 antibody of theinvention and/or at least one immunoconjugate thereof and/or at leastone anti-Robo4 antibody-drug conjugate of the invention. In someembodiments, a pharmaceutical formulation comprises 1) an anti-Robo4antibody and/or an anti-Robo4 antibody-drug conjugate and/or animmunoconjugate thereof, and 2) a pharmaceutically acceptable carrier.In some embodiments, a pharmaceutical formulation comprises 1) ananti-Robo4 antibody and/or an immunoconjugate thereof, and optionally,2) at least one additional therapeutic agent.

Pharmaceutical formulations comprising an antibody or immunoconjugate ofthe invention or the antibody-drug conjugate of the invention areprepared for storage by mixing the antibody or antibody-drug conjugatehaving the desired degree of purity with optional physiologicallyacceptable carriers, excipients or stabilizers (Remington'sPharmaceutical Sciences 16th edition, Osol, A. Ed. (1980)) in the formof aqueous solutions or lyophilized or other dried formulations.Acceptable carriers, excipients, or stabilizers are nontoxic torecipients at the dosages and concentrations employed, and includebuffers such as phosphate, citrate, histidine and other organic acids;antioxidants including ascorbic acid and methionine; preservatives (suchas octadecyldimethylbenzyl ammonium chloride; hexamethonium chloride;benzalkonium chloride, benzethonium chloride); phenol, butyl or benzylalcohol; alkyl parabens such as methyl or propyl paraben; catechol;resorcinol; cyclohexanol; 3-pentanol; and m-cresol); low molecularweight (less than about 10 residues) polypeptides; proteins, such asserum albumin, gelatin, or immunoglobulins; hydrophilic polymers such aspolyvinylpyrrolidone; amino acids such as glycine, glutamine,asparagine, histidine, arginine, or lysine; monosaccharides,disaccharides, and other carbohydrates including glucose, mannose, ordextrins; chelating agents such as EDTA; sugars such as sucrose,mannitol, trehalose or sorbitol; salt-forming counter-ions such assodium; metal complexes (e.g., Zn-protein complexes); and/or non-ionicsurfactants such as TWEEN™, PLURONICS™ or polyethylene glycol (PEG).Pharmaceutical formulations to be used for in vivo administration aregenerally sterile. This is readily accomplished by filtration throughsterile filtration membranes.

Active ingredients may also be entrapped in microcapsule prepared, forexample, by coacervation techniques or by interfacial polymerization,for example, hydroxymethylcellulose or gelatin-microcapsule andpoly-(methylmethacylate) microcapsule, respectively, in colloidal drugdelivery systems (for example, liposomes, albumin microspheres,microemulsions, nano-particles and nanocapsules) or in macroemulsions.Such techniques are disclosed in Remington's Pharmaceutical Sciences16th edition, Osol, A. Ed. (1980).

The formulations to be used for in vivo administration must be sterile.This is readily accomplished by filtration through sterile filtrationmembranes.

Sustained-release preparations may be prepared. Suitable examples ofsustained-release preparations include semipermeable matrices of solidhydrophobic polymers containing the antibody or immunoconjugate of theinvention, which matrices are in the form of shaped articles, e.g.,films, or microcapsule. Examples of sustained-release matrices includepolyesters, hydrogels (for example, poly(2-hydroxyethyl-methacrylate),or poly(vinylalcohol)), polylactides (U.S. Pat. No. 3,773,919),copolymers of L-glutamic acid and y ethyl-L-glutamate, non-degradableethylene-vinyl acetate, degradable lactic acid-glycolic acid copolymerssuch as the LUPRON DEPOT™ (injectable microspheres composed of lacticacid-glycolic acid copolymer and leuprolide acetate), andpoly-D-(−)-3-hydroxybutyric acid. While polymers such as ethylene-vinylacetate and lactic acid-glycolic acid enable release of molecules forover 100 days, certain hydrogels release proteins for shorter timeperiods. When encapsulated antibodies or immunoconjugates remain in thebody for a long time, they may denature or aggregate as a result ofexposure to moisture at 37° C., resulting in a loss of biologicalactivity and possible changes in immunogenicity. Rational strategies canbe devised for stabilization depending on the mechanism involved. Forexample, if the aggregation mechanism is discovered to be intermolecularS—S bond formation through thio-disulfide interchange, stabilization maybe achieved by modifying sulfhydryl residues, lyophilizing from acidicsolutions, controlling moisture content, using appropriate additives,and developing specific polymer matrix compositions.

The formulation herein may also contain more than one active compound asnecessary for the particular indication being treated, preferably thosewith complementary activities that do not adversely affect each other.Such molecules are suitably present in combination in amounts that areeffective for the purpose intended.

C. Combination Therapy

An anti-Robo4 antibodies of the invention may be combined in apharmaceutical combination formulation, or dosing regimen as combinationtherapy, with at least one additional compound having anti-cancerproperties. The at least one additional compound of the pharmaceuticalcombination formulation or dosing regimen preferably has complementaryactivities to the anti-Robo4 antibody composition such that they do notadversely affect each other.

The at least one additional compound may be a chemotherapeutic agent, acytotoxic agent, a cytokine, a growth inhibitory agent, an anti-hormonalagent, and combinations thereof. Such molecules are suitably present incombination in amounts that are effective for the purpose intended. Apharmaceutical composition containing an anti-Robo4 antibody of theinvention may also comprise a therapeutically effective amount of achemotherapeutic agent such as a tubulin-forming inhibitor, atopoisomerase inhibitor, or a DNA binder.

In one aspect, the first compound is an anti-Robo4 ADC of the inventionand the at least one additional compound is a therapeutic antibody otherthan an anti-Robo4 (naked antibody or an ADC). In one embodiment, the atleast one additional compound is an antibody that binds a cancer cellsurface marker. In one embodiment the at least one additional compoundis an anti-HER2 antibody, trastuzumab (e.g., Herceptin®, Genentech,Inc., South San Francisco, Calif.). In one embodiment the at least oneadditional compound is an anti-HER2 antibody, pertuzumab (Omnitarg™,Genentech, Inc., South San Francisco, Calif., see U.S. Pat. No.6,949,245). In one embodiment, the at least one additional compound isan anti-VEGF antibody (e.g., AVASTIN®, Genentech, Inc.). In anembodiment, the at least one additional compound is an antibody (eithera naked antibody or an ADC), and the additional antibody is a second,third, fourth, fifth, sixth antibody or more, such that a combination ofsuch second, third, fourth, fifth, sixth, or more antibodies (eithernaked or as an ADC) is efficacious in treating a cell proliferativedisease in a tissue expressing Robo4.

Other therapeutic regimens may be combined with the administration of ananticancer agent identified in accordance with this invention, includingwithout limitation radiation therapy and/or bone marrow and peripheralblood transplants, and/or a cytotoxic agent, a chemotherapeutic agent,or a growth inhibitory agent. In one of such embodiments, achemotherapeutic agent is an agent or a combination of agents such as,for example, cyclophosphamide, hydroxydaunorubicin, adriamycin,doxorubincin, vincristine (ONCOVIN™), prednisolone, CHOP, CVP, or COP,or immunotherapeutics such as anti-PSCA, anti-HER2 (e.g., HERCEPTIN®,OMNITARG™) or anti-VEGF (e.g., AVASTIN®). The combination therapy may beadministered as a simultaneous or sequential regimen. When administeredsequentially, the combination may be administered in two or moreadministrations. The combined administration includes coadministration,using separate formulations or a single pharmaceutical formulation, andconsecutive administration in either order, wherein preferably there isa time period while both (or all) active agents simultaneously exerttheir biological activities.

In one embodiment, treatment with an anti-Robo4 antibody involves thecombined administration of an anticancer agent identified herein, andone or more chemotherapeutic agents or growth inhibitory agents,including coadministration of cocktails of different chemotherapeuticagents. Chemotherapeutic agents include taxanes (such as paclitaxel anddocetaxel) and/or anthracycline antibiotics. Preparation and dosingschedules for such chemotherapeutic agents may be used according tomanufacturer's instructions or as determined empirically by the skilledpractitioner. Preparation and dosing schedules for such chemotherapy arealso described in “Chemotherapy Service”, (1992) Ed., M. C. Perry,Williams & Wilkins, Baltimore, Md.

Suitable dosages for any of the above coadministered agents are thosepresently used and may be lowered due to the combined action (synergy)of the newly identified agent and other chemotherapeutic agents ortreatments.

The combination therapy may provide “synergy” and prove “synergistic”,i.e. the effect achieved when the active ingredients used together isgreater than the sum of the effects that results from using thecompounds separately. A synergistic effect may be attained when theactive ingredients are: (1) co-formulated and administered or deliveredsimultaneously in a combined, unit dosage formulation; (2) delivered byalternation or in parallel as separate formulations; or (3) by someother regimen. When delivered in alternation therapy, a synergisticeffect may be attained when the compounds are administered or deliveredsequentially, e.g. by different injections in separate syringes. Ingeneral, during alternation therapy, an effective dosage of each activeingredient is administered sequentially, i.e. serially, whereas incombination therapy, effective dosages of two or more active ingredientsare administered together.

For the prevention or treatment of disease, the appropriate dosage of anantibody of the invention (when used alone or in combination with otheragents such as chemotherapeutic agents) will depend on the type ofdisease to be treated, the type of antibody, the severity and course ofthe disease, whether the antibody is administered for preventive ortherapeutic purposes, previous therapy, the patient's clinical historyand response to the antibody, and the discretion of the attendingphysician. The antibody is suitably administered to the patient at onetime or over a series of treatments. Depending on the type and severityof the disease, about 1 μg/kg to 15 mg/kg (e.g. 0.1 mg/kg-10 mg/kg) ofantibody is an initial candidate dosage for administration to thepatient, whether, for example, by one or more separate administrations,or by continuous infusion. One typical daily dosage might range fromabout 1 μg/kg to 100 mg/kg or more, depending on the factors mentionedabove. For repeated administrations over several days or longer,depending on the condition, the treatment is sustained until a desiredsuppression of disease symptoms occurs. One exemplary dosage of theantibody would be in the range from about 0.05 mg/kg to about 10 mg/kg.Thus, one or more doses of about 0.5 mg/kg, 2.0 mg/kg, 4.0 mg/kg or 10mg/kg (or any combination thereof) may be administered to the patient.Such doses may be administered intermittently, e.g. every week or everythree weeks (e.g. such that the patient receives from about two to abouttwenty, e.g. about six doses of the antibody). An initial higher loadingdose, followed by one or more lower doses may be administered. Anexemplary dosing regimen comprises administering an initial loading doseof about 4 mg/kg, followed by a weekly maintenance dose of about 2 mg/kgof the antibody. However, other dosage regimens may be useful. Theprogress of this therapy is easily monitored by conventional techniquesand assays.

IX. Labeled Antibodies and Uses Thereof

The invention also provides labeled anti-Robo4 antibodies. Labeledantibodies may be useful in diagnostic assays, e.g., in vitro, ex vivo,or in vivo assays for detecting expression of Robo4 in specific cells ortissues (e.g., to image angiogenesis, neovascularization, and/or tumorvasculature). In some embodiments, the labeled antibodies are used in invivo imaging assays. The anti-Robo4 antibodies of the invention, may beconjugated with any label moiety which can be covalently attached to theantibody. In some embodiments, the anti-Robo4 antibodies of theinvention (including, e.g., the cysteine engineered anti-Robo4antibodies) are covalently attached to the antibody through a reactivegroup on the antibody, such as a reactive lysine or cysteine residue.Covalent attachment through a reactive cysteine thiol group is disclosedin Singh et al., Anal. Biochem. 304:147-15 (2002); Harlow E. and Lane,D. (1999) Using Antibodies: A Laboratory Manual, Cold Springs HarborLaboratory Press, Cold Spring Harbor, N.Y.; Lundblad R. L. (1991)Chemical Reagents for Protein Modification, 2nd ed. CRC Press, BocaRaton, Fla.

The attached label may function to: (i) provide a detectable signal;(ii) interact with a second label to modify the detectable signalprovided by the first or second label, e.g. to give FRET (fluorescenceresonance energy transfer); (iii) stabilize interactions or increaseaffinity of binding, with antigen or ligand; (iv) affect mobility, e.g.electrophoretic mobility or cell-permeability, by charge,hydrophobicity, shape, or other physical parameters, or (v) provide acapture moiety, to modulate ligand affinity, antibody/antigen binding,or ionic complexation.

For diagnostic applications, the antibody will typically be labeled witha detectable moiety. Numerous labels are available which can begenerally grouped into the following categories:

(a) In some embodiments, the anti-Robo4 antibodies are labeled withradioisotopes (radionuclides), such as ³H, ¹¹C, ¹⁴C, ¹⁸F, ¹⁹F, ³²P, ³⁵S,⁶⁴Cu, ⁶⁸Ga, ⁸⁶Y, ⁹⁹Tc, ¹¹¹In, ¹²³I, ¹²⁴I, ¹²⁵I, ¹³¹I, ¹³³Xe, ¹⁷⁷Lu,²¹¹At, or ²¹³Bi. Radioisotope labeled anti-Robo4 antibodies are usefulin receptor targeted imaging of cells expressing Robo4, (e.g., for usein the diagnostic uses of the invention such as in vivo imaging of tumorendothelial cells, tumor vasculature, angiogenesis, andneovascularization).

(b) In some embodiments, the anti-Robo4 antibodies are labeled withligand reagents that bind, chelate or otherwise complex a radioisotopemetal where the reagent is reactive with the engineered cysteine thiolof the antibody, using the techniques described in Current Protocols inImmunology, Volumes 1 and 2, Coligen et al, Ed. Wiley-Interscience, NewYork, N.Y., Pubs. (1991). Chelating ligands which may complex a metalion include DOTA, DOTP, DOTMA, DTPA and TETA (Macrocyclics, Dallas,Tex.). Chelating linker reagents such as DOTA-maleimide(4-maleimidobutyramidobenzyl-DOTA) can be prepared by the reaction ofaminobenzyl-DOTA with 4-maleimidobutyric acid (Fluka) activated withisopropylchloroformate (Aldrich), following the procedure of Axworthy etal. (2000) PNAS USA 97(4):1802-1807). DOTA-maleimide reagents react withthe free cysteine amino acids of the cysteine engineered antibodies andprovide a metal complexing ligand on the antibody (Lewis et al.,Bioconj. Chem. 9:72-86 (1998)). Chelating linker labelling reagents suchas DOTA-NHS (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acidmono (N-hydroxysuccinimide ester) are commercially available(Macrocyclics, Dallas, Tex.). Radionuclides can be targeted viacomplexation with the antibody-drug conjugates of the invention (Wu etal. Nature Biotech. 23(9): 1137-1146 (2005)). Receptor target imagingwith radionuclide labeled antibodies can provide a marker of increasedtarget expression by detection and quantitation of progressiveaccumulation of antibodies in tumor tissue (Albert et al. Bioorg. Med.Chem. Lett. 8:1207-1210 (1998)). The conjugated radio-metals may remainintracellular following lysosomal degradation.

Metal-chelate complexes suitable as antibody labels for imagingexperiments are disclosed: U.S. Pat. No. 5,342,606; U.S. Pat. No.5,428,155; U.S. Pat. No. 5,316,757; U.S. Pat. No. 5,480,990; U.S. Pat.No. 5,462,725; U.S. Pat. No. 5,428,139; U.S. Pat. No. 5,385,893; U.S.Pat. No. 5,739,294; U.S. Pat. No. 5,750,660; U.S. Pat. No. 5,834,456;Hnatowich et al. (1983) J. Immunol. Methods 65:147-157; Meares et al.,Anal. Biochem. 142:68-78 (1984); Mirzadeh et al., Bioconjugate Chem.1:59-65 (1990); Meares et al., J. Cancer, Suppl. 10:21-26 (1990); Izardet al., Bioconjugate Chem. 3:346-350 (1992); Nikula et al., Nucl. Med.Biol. 22:387-90 (1995); Camera et al., Nucl. Med. Biol. 20:955-62(1993); Kukis et al., J. Nucl. Med. 39:2105-2110 (1998); Verel et al.,J. Nucl. Med. 44:1663-1670 (2003); Camera et al., J. Nucl. Med.21:640-646 (1994); Ruegg et al., Cancer Res. 50:4221-4226 (1990); Verelet al., J. Nucl. Med. 44:1663-1670 (2003); Lee et al., Cancer Res.61:4474-4482 (2001); Mitchell, et al., J. Nucl. Med. 44:1105-1112(2003); Kobayashi et al., Bioconjugate Chem. 10:103-111 (1999); Miedereret al., J. Nucl. Med. 45:129-137 (2004); DeNardo et al., Clinical CancerResearch 4:2483-90 (1998); Blend et al., Cancer Biotherapy &Radiopharmaceuticals 18:355-363 (2003); Nikula et al., J. Nucl. Med.40:166-76 (1999); Kobayashi et al., J. Nucl. Med. 39:829-36 (1998);Mardirossian et al., Nucl. Med. Biol. 20:65-74 (1993); Roselli et al.,Cancer Biotherapy & Radiopharmaceuticals, 14:209-20 (1999).

(c) In some embodiments, the anti-Robo4 antibodies are labeled withfluorescent labels such as rare earth chelates (europium chelates),fluorescein types including FITC, 5-carboxyfluorescein, 6-carboxyfluorescein; rhodamine types including TAMRA; dansyl; Lissamine;cyanines; phycoerythrins; Texas Red; and analogs thereof. Thefluorescent labels can be conjugated to antibodies using the techniquesdisclosed in Current Protocols in Immunology, supra, for example.Fluorescent dyes and fluorescent label reagents include those which arecommercially available from Invitrogen/Molecular Probes (Eugene, Oreg.)and Pierce Biotechnology, Inc. (Rockford, Ill.).

(d) In some embodiments, the anti-Robo4 antibodies are labeled withvarious enzyme-substrate labels are available or disclosed (U.S. Pat.No. 4,275,149). The enzyme generally catalyzes a chemical alteration ofa chromogenic substrate that can be measured using various techniques.For example, the enzyme may catalyze a color change in a substrate,which can be measured spectrophotometrically. Alternatively, the enzymemay alter the fluorescence or chemiluminescence of the substrate.Techniques for quantifying a change in fluorescence are described above.The chemiluminescent substrate becomes electronically excited by achemical reaction and may then emit light which can be measured (using achemiluminometer, for example) or donates energy to a fluorescentacceptor. Examples of enzymatic labels include luciferases (e.g.,firefly luciferase and bacterial luciferase; U.S. Pat. No. 4,737,456),luciferin, 2,3-dihydrophthalazinediones, malate dehydrogenase, urease,peroxidase such as horseradish peroxidase (HRP), alkaline phosphatase(AP), -galactosidase, glucoamylase, lysozyme, saccharide oxidases (e.g.,glucose oxidase, galactose oxidase, and glucose-6-phosphatedehydrogenase), heterocyclic oxidases (such as uricase and xanthineoxidase), lactoperoxidase, microperoxidase, and the like. Techniques forconjugating enzymes to antibodies are described in O'Sullivan et al.(1981) “Methods for the Preparation of Enzyme-Antibody Conjugates foruse in Enzyme Immunoassay”, in Methods in Enzym. (ed J. Langone & H. VanVunakis), Academic Press, New York, 73:147-166.

Examples of enzyme-substrate combinations include, for example:

(i) Horseradish peroxidase (HRP) with hydrogen peroxidase as asubstrate, wherein the hydrogen peroxidase oxidizes a dye precursor(e.g., orthophenylene diamine (OPD) or 3,3′,5,5′-tetramethylbenzidinehydrochloride (TMB));

(ii) alkaline phosphatase (AP) with para-nitrophenyl phosphate aschromogenic substrate; and

(iii) -D-galactosidase (-D-Gal) with a chromogenic substrate (e.g.,p-nitrophenyl-D-galactosidase) or fluorogenic substrate4-methylumbelliferyl-D-galactosidase.

Numerous other enzyme-substrate combinations are available to thoseskilled in the art. For a general review, see U.S. Pat. No. 4,275,149and U.S. Pat. No. 4,318,980.

A label may be indirectly conjugated with an anti-Robo4 antibody(including, e.g., a cysteine engineered anti-Robo4 antibody). Forexample, the anti-Robo4 antibody can be conjugated with biotin and anyof the three broad categories of labels mentioned above can beconjugated with avidin or streptavidin, or vice versa. Biotin bindsselectively to streptavidin and thus, the label can be conjugated withthe anti-Robo4 antibody in this indirect manner. Alternatively, toachieve indirect conjugation of the label with the anti-Robo4 antibody,the anti-Robo4 antibody is conjugated with a small hapten (e.g.,digoxin) and one of the different types of labels mentioned above isconjugated with an anti-hapten polypeptide variant (e.g., anti-digoxinantibody). Thus, indirect conjugation of the label with the anti-Robo4antibody can be achieved (Hermanson, G. (1996) in BioconjugateTechniques Academic Press, San Diego).

The anti-Robo4 antibody of the present invention may be employed in anyknown assay method, such as ELISA, competitive binding assays, directand indirect sandwich assays, and immunoprecipitation assays (Zola,(1987) Monoclonal Antibodies: A Manual of Techniques, pp. 147-158, CRCPress, Inc.).

The labeled anti-Robo4 antibodies of the invention can detectcell-surface receptors and are useful for localizing, visualizing, andquantitating endothelial cells (e.g., tumor endothelial cells), sites ofangiogenesis, sites of neovascularization, and/or tumor vasculature.Another use for detectably labeled antibodies is a method of bead-basedimmunocapture comprising conjugating a bead with a fluorescent labeledantibody and detecting a fluorescence signal upon binding of a ligand.Similar binding detection methodologies utilize the surface plasmonresonance (SPR) effect to measure and detect antibody-antigeninteractions. The detectably labeled anti-Robo4 antibody of the presentinvention may be employed in any known assay method, such as ELISA,competitive binding assays, direct and indirect sandwich assays, andimmunoprecipitation assays (Zola, (1987) Monoclonal Antibodies: A Manualof Techniques, pp. 147-158, CRC Press, Inc.).

Detection labels such as fluorescent dyes and chemiluminescent dyes(Briggs et al, J. Chem. Soc., Perkin-Trans. 1:1051-1058 (1997)) providea detectable signal and are generally applicable for labellingantibodies, preferably with the following properties: (i) the labeledantibody should produce a very high signal with low background so thatsmall quantities of antibodies can be sensitively detected in bothcell-free and cell-based assays; and (ii) the labeled antibody should bephotostable so that the fluorescent signal may be observed, monitoredand recorded without significant photo bleaching. For applicationsinvolving cell surface binding of labeled antibody to membranes or cellsurfaces, especially live cells, the labels preferably (iii) have goodwater-solubility to achieve effective conjugate concentration anddetection sensitivity and (iv) are non-toxic to living cells so as notto disrupt the normal metabolic processes of the cells or causepremature cell death.

Direct quantification of cellular fluorescence intensity and enumerationof fluorescently labeled events, e.g. cell surface binding ofpeptide-dye conjugates may be conducted on an system (FMAT® 8100 HTSSystem, Applied Biosystems, Foster City, Calif.) that automatesmix-and-read, non-radioactive assays with live cells or beads (Miraglia,“Homogeneous cell- and bead-based assays for high throughput screeningusing fluorometric microvolume assay technology”, (1999) J. ofBiomolecular Screening 4:193-204). Uses of labeled antibodies alsoinclude cell surface receptor binding assays, immunocapture assays,fluorescence linked immunosorbent assays (FLISA), caspase-cleavage(Zheng, “Caspase-3 controls both cytoplasmic and nuclear eventsassociated with Fas-mediated apoptosis in vivo”, (1998) PNAS USA95:618-23; U.S. Pat. No. 6,372,907), apoptosis (Vermes, J. Immunol.Methods 184:39-51 (1995)) and cytotoxicity assays. Fluorometricmicrovolume assay technology can be used to identify the up or downregulation by a molecule that is targeted to the cell surface(Swartzman, Anal. Biochem. 271:143-51 (1999)).

Labeled cysteine engineered antibodies of the invention are useful asimaging biomarkers and probes by the various methods and techniques ofbiomedical and molecular imaging such as: (i) MRI (magnetic resonanceimaging); (ii) X-ray computed tomography); (iii) SPECT (single photonemission computed tomography); (iv) PET (positron emission tomography)Chen et al. (2004) Bioconjugate Chem. 15:41-49; (v) bioluminescence;(vi) fluorescence; and (vii) ultrasound. Immunoscintigraphy is animaging procedure in which antibodies labeled with radioactivesubstances are administered to an animal or human patient and a pictureis taken of sites in the body (e.g., tumors including tumor vasculature,or metastases thereof) where the antibody localizes (U.S. Pat. No.6,528,624). Imaging biomarkers may be objectively measured and evaluatedas an indicator of normal biological processes, pathogenic processes, orpharmacological responses to a therapeutic intervention. Biomarkers maybe of several types: Type 0 are natural history markers of a disease andcorrelate longitudinally with known clinical indices, e.g. MRIassessment of synovial inflammation in rheumatoid arthritis; Type Imarkers capture the effect of an intervention in accordance with amechanism-of-action, even though the mechanism may not be associatedwith clinical outcome; Type II markers function as surrogate endpointswhere the change in, or signal from, the biomarker predicts a clinicalbenefit to “validate” the targeted response, such as measured boneerosion in rheumatoid arthritis by planar X-ray, MRI or CT. Imagingbiomarkers thus can provide pharmacodynamic (PD) therapeutic informationabout: (i) expression of a target protein, (ii) binding of a therapeuticto the target protein, i.e. selectivity, and (iii) clearance andhalf-life pharmacokinetic data. Advantages of in vivo imaging biomarkersrelative to lab-based biomarkers include: non-invasive treatment,quantifiable, whole body assessment, repetitive dosing and assessment,i.e. multiple time points, and potentially transferable effects frompreclinical (small animal) to clinical (human) results. For someapplications, bioimaging supplants or minimizes the number of animalexperiments in preclinical studies.

Peptide labelling methods are well known. See Haugland, 2003, MolecularProbes Handbook of Fluorescent Probes and Research Chemicals, MolecularProbes, Inc.; Brinkley, 1992, Bioconjugate Chem. 3:2; Garman, (1997)Non-Radioactive Labelling: A Practical Approach, Academic Press, London;Means (1990) Bioconjugate Chem. 1:2; Glazer et al. (1975) ChemicalModification of Proteins. Laboratory Techniques in Biochemistry andMolecular Biology (T. S. Work and E. Work, Eds.) American ElsevierPublishing Co., New York; Lundblad, R. L. and Noyes, C. M. (1984)Chemical Reagents for Protein Modification, Vols. I and II, CRC Press,New York; Pfleiderer, G. (1985) “Chemical Modification of Proteins”,Modern Methods in Protein Chemistry, H. Tschesche, Ed., Walter DeGryter,Berlin and New York; and Wong (1991) Chemistry of Protein Conjugationand Cross-linking, CRC Press, Boca Raton, Fla.); De Leon-Rodriguez etal. (2004) Chem. Eur. J. 10:1149-1155; Lewis et al. (2001) BioconjugateChem. 12:320-324; Li et al. (2002) Bioconjugate Chem. 13:110-115; Mieret al. (2005) Bioconjugate Chem. 16:240-237.

Peptides and proteins labeled with two moieties, a fluorescent reporterand quencher in sufficient proximity undergo fluorescence resonanceenergy transfer (FRET). Reporter groups are typically fluorescent dyesthat are excited by light at a certain wavelength and transfer energy toan acceptor, or quencher, group, with the appropriate Stokes shift foremission at maximal brightness. Fluorescent dyes include molecules withextended aromaticity, such as fluorescein and rhodamine, and theirderivatives. The fluorescent reporter may be partially or significantlyquenched by the quencher moiety in an intact peptide. Upon cleavage ofthe peptide by a peptidase or protease, a detectable increase influorescence may be measured (Knight, C. (1995) “Fluorimetric Assays ofProteolytic Enzymes”, Methods in Enzymology, Academic Press, 248:18-34).

The anti-Robo4 labeled antibodies of the invention may also be used asan affinity purification agent. In this process, the labeled antibody isimmobilized on a solid phase such a Sephadex resin or filter paper,using methods well known in the art. The immobilized antibody iscontacted with a sample containing the antigen to be purified, andthereafter the support is washed with a suitable solvent that willremove substantially all the material in the sample except the antigento be purified, which is bound to the immobilized antibody. Finally, thesupport is washed with another suitable solvent, such as glycine buffer,pH 5.0, that will release the antigen from the antibody.

Labelling reagents typically bear reactive functionality which may react(i) directly with a cysteine thiol of a cysteine engineered antibody toform the labeled antibody, (ii) with a linker reagent to form alinker-label intermediate, or (iii) with a linker antibody to form thelabeled antibody. Reactive functionality of labelling reagents include:maleimide, haloacetyl, iodoacetamide succinimidyl ester (e.g. NHS,N-hydroxysuccinimide), isothiocyanate, sulfonyl chloride,2,6-dichlorotriazinyl, pentafluorophenyl ester, and phosphoramidite,although other functional groups can also be used.

An exemplary reactive functional group is N-hydroxysuccinimidyl ester(NHS) of a carboxyl group substituent of a detectable label, e.g. biotinor a fluorescent dye. The NHS ester of the label may be preformed,isolated, purified, and/or characterized, or it may be formed in situand reacted with a nucleophilic group of an antibody. Typically, thecarboxyl form of the label is activated by reacting with somecombination of a carbodiimide reagent, e.g. dicyclohexylcarbodiimide,diisopropylcarbodiimide, or a uronium reagent, e.g. TSTU(O—(N-Succinimidyl)-N,N,N′,N′-tetramethyluronium tetrafluoroborate, HBTU(O-benzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate),or HATU (O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluroniumhexafluorophosphate), an activator, such as 1-hydroxybenzotriazole(HOBt), and N-hydroxysuccinimide to give the NHS ester of the label. Insome cases, the label and the antibody may be coupled by in situactivation of the label and reaction with the antibody to form thelabel-antibody conjugate in one step. Other activating and couplingreagents include TBTU(2-(1H-benzotriazo-1-yl)-1-1,3,3-tetramethyluroniumhexafluorophosphate), TFFH(N,N′,N″,N′″-tetramethyluronium2-fluoro-hexafluorophosphate), PyBOP(benzotriazole-1-yl-oxy-tris-pyrrolidino-phosphoniumhexafluorophosphate, EEDQ(2-ethoxy-1-ethoxycarbonyl-1,2-dihydro-quinoline), DCC(dicyclohexylcarbodiimide); DIPCDI (diisopropylcarbodiimide), MSNT(1-(mesitylene-2-sulfonyl)-3-nitro-1H-1,2,4-triazole, and aryl sulfonylhalides, e.g. triisopropylbenzenesulfonyl chloride.

A detectably labeled antibody of the invention may be detectable bybeing linked to (including covalently conjugated to) a magnetic particleor nanoparticle or metallic particle or nanoparticle. Metallic particlesare detectable by such methods as magnetic resonance imaging (MRI),single-particle or single-molecule tracking, immunocytochemistry,plasmon frequency with dark-field illumination, differentialinterference contrast and video enhancement, total internal reflection,and photothermal interference contrast (PIC) technique (see, for examplePNAS USA 100(20): 11350-11355 (2003); Sheetz et al. Nature 340:284-288(1989); Baschong et al., Histochemistry 83:409-411 (1985); Slot andGeuze, Eur. J. Cell Biol. 38:87-93 (1935); Frey and Frey J. Struct.Biol. 127:94-100 (1999); Hainfeld and Powell, J. Histochem. Cytochem.48:471-480 (2000); Schultz et al. PNAS USA 97:996-1001 (2000); Gelles etal., Nature 331:450-453 (1988); Sonnichsen et al., Appl Phys. Lett.77:2949-2951 (2000); Boyer, D. et al., Science 297:1160-1163 (2002)).Anti-Robo4 antibodies of the invention may comprise nanoparticulateagents including, but not limited to, microbubbles (see Ellegala et al.,Circulation 108:336-341 (2003))), also referred to as acousticallyactive lipospheres (AALs) (see Tartis et al., Ultrasound Med. Biol.32(11):1771-80 (2006)), superparamagnetic agents, liposomes,perfluorocarbon nanoparticle emulsions (WO2005014051), and dendrimers(see Caruthers et al., Methods in Molecular Medicine, 124:387-400 (2006)and references cited therein, all of which references are herebyincorporated by reference in their entirety).

When the labeled anti-Robo4 antibodies are used for detection (e.g., inscintigraphic studies), the labels may comprise a radioactive atom(e.g., At²¹¹, I¹³¹, I¹²⁵, Y⁹⁰, Re¹⁸⁶, Re¹⁸⁸, Sm¹⁵³, Bi²¹², P³², Pb²¹²and radioactive isotopes of Lu) or a spin label for nuclear magneticresonance (NMR) imaging (also known as magnetic resonance imaging, mri),such as Tc^(99m), ¹²³I, ¹¹¹In, ¹³¹I, ¹⁹F, ¹H, ¹⁴N, ¹⁵N, ¹⁷O, ²³Na, ³¹P,or ¹³C, gadolinium, manganese, iron, or iron oxides (e.g.,super-paramagnetic iron oxide particles (SPIL) or ultra-smallparamagnetic iron oxide particles (USPIL)), or other NMR observableagents.

X. Articles of Manufacture

In another aspect of the invention, an article of manufacture containingmaterials useful for the treatment, prevention and/or diagnosis of thedisorders described above is provided. The article of manufacturecomprises a container and a label or package insert on or associatedwith the container. Suitable containers include, for example, bottles,vials, syringes, etc. The containers may be formed from a variety ofmaterials such as glass or plastic. The container holds a compositionwhich is by itself or when combined with another composition effectivefor treating, preventing and/or diagnosing the condition and may have asterile access port (for example the container may be an intravenoussolution bag or a vial having a stopper pierceable by a hypodermicinjection needle). At least one active agent in the composition is anantibody of the invention. The label or package insert indicates thatthe composition is used for treating the condition of choice, such ascancer. Moreover, the article of manufacture may comprise (a) a firstcontainer with a composition contained therein, wherein the compositioncomprises an antibody of the invention; and (b) a second container witha composition contained therein, wherein the composition comprises afurther cytotoxic agent. The article of manufacture in this embodimentof the invention may further comprise a package insert indicating thatthe first and second antibody compositions can be used to treat aparticular condition, e.g. cancer. Alternatively, or additionally, thearticle of manufacture may further comprise a second (or third)container comprising a pharmaceutically-acceptable buffer, such asbacteriostatic water for injection (BWFI), phosphate-buffered saline,Ringer's solution and dextrose solution. It may further include othermaterials desirable from a commercial and user standpoint, includingother buffers, diluents, filters, needles, and syringes.

The following are examples of the methods and compositions of theinvention. It is understood that various other embodiments may bepracticed, given the general description provided above.

EXAMPLES

Amino acid residues within antibody amino acid sequences are numberedaccording to Kabat (Kabat et al., Sequences of proteins of immunologicalinterest, 5th Ed., Public Health Service, National Institutes of Health,Bethesda, Md. (1991)). Single letter amino acid abbreviations are used.DNA degeneracies are represented using the IUB code (N=A/C/G/T, D=A/G/T,V=A/C/G, B=C/G/T, H=A/C/T, K=G/T, M=A/C, R=A/G, S=G/C, W=A/T, Y=C/T).

Example 1 Antibodies Derived from Phage Encoding Hypervariable Regionsof a Starting Antibody

The nucleic acid sequences of the VL and VH domains of the HERCEPTIN®anti-HER2 antibody rhuMAB 4D5-8 (Genentech, Inc.) was used as thestarting sequence for mutagenesis of the HVRs and phage selection forbinding to human Robo4 His-tagged antigen shown in FIG. 5B or humanRob4-Fc fusion protein. Antibody 4D5 is a humanized antibody specificfor a cancer-associated antigen known as Her-2 (erbB2). The antibodyincludes variable domains having consensus framework regions; a fewpositions were reverted to mouse sequence during the process ofincreasing affinity of the humanized antibody. The sequence and crystalstructure of humanized antibody 4D5 have been described in U.S. Pat. No.6,054,297, Carter et al, PNAS USA 89:4285 (1992), the crystal structureis shown in J. Mol. Biol. 229:969 (1993) and online. The HERCEPTIN® VLand VH domains comprise the consensus human kappa I VL domain and avariant of the human subgroup III consensus VH domain, respectively. Thevariant VH domain has 3 changes from the human consensus: R71A, N73T andL78A.

The phagemid used for this work is a monovalent Fab-g3 display vector(pV0350-2B) having 2 open reading frames under control of the phoApromoter, essentially as described in Lee et al., J. Mol. Biol. (2004),340(5): 1073-93. The first open reading frame consists of the stIIsignal sequence fused to the VL and CH1 domains acceptor light chain andthe second consists of the stII signal sequence fused to the VH and CH1domains of the acceptor heavy chain followed by a truncated minor phagecoat protein P3. See Lee et al., J. Mol. Biol. (2004), 340(5):1073-93.

Example 2 Antibodies Generated by Mutagenesis of Heavy Chain HVRs

Fab clones YW71.6, YW71.1, YW71.22, and YW71.89 were generated bymutagenesis of HVR-H1, H2, and H3 of huMAb 4D5-8 (HERCEPTIN® anti-BER2antibody, Genentech, Inc.) heavy chain and selection against humanRobo4-His tagged antigen fusion protein. In HVR-H1, Kabat positions 26(G), 27 (F), 28 (T), 29 (I), 34 (I), and 35 (H) were held constant, andthe amino acids at positions 30-33 were varied. In HVR-H2, Kabatpositions 51 (I), 52a (P), 55 (G), 57 (T), 59 (Y), 60 (A), 61 (D), 62(S), 63 (V), 64 (K), and 65 (G) were held constant, and positions 49,50, 52, 53, 54, 56, and 58 were varied. In HVR-H3, Kabat positions 93(A) and 102 (Y) were held constant, and positions 94-100, 100a-h, and101 were varied. The light chain of YW71.22 was the modified huMAb 4D5-8sequence (modified at positions 30, 66 and 91 resulting in SEQ IDNO:168, comprising SEQ ID NOS:1, 2, and 3 as HVR-L1, L2, and L3,respectively), the HVRs of which were not varied during phage selection.Sequence diversity was introduced into each hypervariable region bymutagenesis of selected amino acid positions using standard mutagenesistechniques.

Generation of phage libraries—Randomized oligonucleotide pools designedfor each hypervariable region were phoshorylated separately in six 20 μlreactions containing 660 ng of oligonucleotide, 50 mM Tris pH 7.5, 10 mMMgCl₂, 1 mM ATP, 20 mM DTT, and 5 U polynucleotide kinase for 1 h at 37°C. The six phosphorylated oligonucleotide pools were then combined with20 μg of Kunkel template in 50 mM Tris pH 7.5, 10 mM MgCl₂ in a finalvolume of 500 μl resulting in an oligonucleotide to template ratio of 3.The mixture was annealed at 90° C. for 4 min, 50° C. for 5 min and thencooled on ice. Excess, unannealed oligonucleotide was removed with aQIAQUICK™ PCR purification kit (Qiagen kit 28106) using a modifiedprotocol to prevent excessive denaturation of the annealed DNA. To the500 μl of annealed mixture, 150 μl of PB was added, and the mixture wassplit between 2 silica columns. Following a wash of each column with 750μl of PE and an extra spin to dry the columns, each column was elutedwith 110 μl of 10 mM Tris, 1 mM EDTA, pH 8. The annealed and cleaned-uptemplate (220 μl) was then filled in by adding 1 μl 100 mM ATP, 10 μl 25mM dNTPs (25 mM each of dATP, dCTP, dGTP and dTTP), 15 μl 100 mM DTT, 25μl 10×TM buffer (0.5 M Tris pH 7.5, 0.1 M MgCl₂), 2400 U T4 ligase, and30 U T7 polymerase for 3 h at room temperature.

The filled in product was analyzed on Tris-Acetate-EDTA/agarose gels(Sidhu et al., Methods in Enzymology 328:333-363 (2000)). Three bandswere usually visible: the bottom band is a correctly filled and ligatedproduct, the middle band is a filled but unligated product, and the topband is a strand displaced product. The top band is produced by anintrinsic side activity of T7 polymerase and is difficult to avoid(Lechner et al., J. Biol. Chem. 258:11174-11184 (1983)); however, thisband transforms 30-fold less efficiently than the bottom band andusually contributes little to the library. The middle band is due to theabsence of a 5′ phosphate for the final ligation reaction; this bandtransforms efficiently and gives mainly wild type sequence.

The filled in product was then purified and electroporated into SS320cells and propagated in the presence of M13/KO7 helper phage asdescribed by Sidhu et al., Methods in Enzymology 328:333-363 (2000).Library sizes ranged from 1-2×10⁹ independent clones. Random clones fromthe initial libraries were sequenced to assess library quality.

Phage Selection—The human Robo4-Fc and Robo4-His-tagged proteins wereused as the selection antigens. Human Robo4-Fc and Robo4-His was coatedon MaxiSorp microtiter plates (Nunc) at 10 μg/mil in PBS and incubatedovernight at 4 degrees. For the first round of selection 12 wells oftarget were used. Wells were blocked for 1 hour at room temperatureusing Phage Blocking Buffer (1% BSA, 0.05% Tween® 20, PBS). Phagelibraries were PEG precipitates from frozen glycerol stocks, resuspendedin Phage Blocking Buffer and incubated for 1 hour at room temperature.Phage libraries were then added to the blocked antigen plates incubatedovernight at room temperature. After overnight binding, unbound ornon-specifically bound phage were removed from the antigen plates bywashing with Wash Buffer (PBS, 05% Tween®20). Bound phage were eluted byincubating the wells with 50 mM HCl, 0.5 M KCl for 30 min. Phage wereamplified using XL-1 Blue cells and M13/KO7 helper phage and grown for36 hours at 30° C. in 2YT, 50 μg/ml carbanecillin, 50 ug/ml kanamycin,10 μg/ml tetracycline. Amplified phage were then recovered using amodified PEG precipitation protocol (Clackson & Lowman 2004). The titersof phage eluted from a target coated well were compared to titers ofphage recovered from a non-target coated well to assess enrichment. Fourrounds of phage selection were completed with the number of target wellsdecreasing to 4 (round 2) and 2 (round 3 and 4). Casein Blocking Buffer(Pierce) was used as the blocking reagent for antigen plates and phagefor rounds 2 and 4. Selection rounds 2-4 used a 3-4 hour phage-antigenbinding period and increased washing stringency. Four phage clones wereselected: YW71.6, YW7.1, YW71.22, and YW71.89. The sequences of thelight and heavy chain domains were determined and are shown in FIGS. 1Aand 1B. The Robo4 binding characteristics were determined as disclosedherein below.

Example 3 Antibodies Generated by Variation of HVRs H1, H2, H3 and L3

Clones YW79.1, YW79.8, and YW79.11 were generated by mutagenesis ofHVR-H1, H2, H3 and L3 of huMAb 4D5-8 (HERCEPTIN® anti-HER2 antibody,Genentech, Inc.) heavy chain variable domain and huMAb 4D5-8 modifiedlight chain variable domain, SEQ ID NO:168. In HVR-H1, Kabat positions26 (G), 28 (T), 29 (F), 30 (S), 31 (S), and 35 (S) were held constant,and the amino acids at positions 27, 32-34 were varied. In HVR-H2, Kabatpositions 49 (S), 51 (I), 55 (G), 57 (T), 59 (Y), 60 (A), 61 (D), 62(S), 63 (V), 64 (K), and 65 (G) were held constant, and positions 50,52, 52a, 53, 54, 56, and 58 were varied. In HVR-H3, Kabat positions 93(A), 94 (R), 100f-g (deletion) were held constant, and positions 95-100,100a-e, 100h, and 102 were varied. In HVR-L3, Kabat positions 89 (Q), 90(Q), 95 (P) and 97 (T) were held constant, and positions 91-94 and 96were varied. The sequence of HVR-L1 was held constant as RASQSISSYLA(SEQ ID NO:7) and the sequence of HVR-L2 was held constant as GASSRAS(SEQ ID NO:8). Sequence diversity was introduced into each hypervariableregion by mutagenesis of selected amino acid positions using standardmutagenesis techniques. Anti-Robo4 antibody clones YW79.1, YW79.8, andYW79.11 were selected and sequenced. The sequences of the light chainand heavy chain variable regions are shown in FIGS. 1A and 1B.

Example 4 Purification of Soluble Robo4 and Anti-Robo4 Antibodies

This example describes methods useful in the purification of the Robo4antigen and the anti-Robo4 antibodies of the invention. Robo4 antigenwas purified as a soluble Robo4 extracellular domain fused to ahistidine tag as shown in FIG. 5B.

Robo4 Antigen Purification

Human Robo4 constructs (amino acid M1 to amino acid L461 and amino acidM1 to amino acid Y231) were cloned into the eukaryotic expression vectorpRK5 either as fusions to the Fc portion of human IgG1 or to aC-terminal Histidine tag. Murine Robo4 (M1 to H232) was cloned into pRK5as fusion to a C-terminal Histidine tag only. All proteins were producedby transient transfection of CHO cells. Proteins were purified to >90%purity by affinity chromatography using either protein-A Sepharose™ (GEHealthcare) for Fc fusion proteins or NiNTA Superflow™ (Qiagen) forHistidine tag fusions. If necessary an ion exchange chromatography step(Q- or SP-Sepharose™, GE Healthcare) was added and/or a size exclusionchromatography step (Superdex™ 75, GE Healthcare). Protein identitieswere confirmed by N-terminal sequencing using the Edman degradationmethod, concentrations were determined by the BCA assay and by OD 280absorption measurements, and purity was assessed by size exclusionchromatography and SDS-PAGE.

Antibody Purification

Full length Robo4 antibodies were transiently expressed in CHO cells andpurified to >95% purity by affinity chromatography using protein-ASepharose™ (GE Healthcare), followed by ion exchange chromatographyusing SP-Sepharose™ (GE Healthcare). If necessary, an additional sizeexclusion chromatography step (Superdex™ 200, GE Healthcare) was added.Antibody concentrations were determined by the BCA assay according tomanufacturer's instructions (Pierce Chemical Co.) and by OD 280absorption measurements, and purity was assessed by size exclusionchromatography and SDS-PAGE. For all antibody purifications, aggregatelevels as determined by laser light scattering were below 5%, protein Alevels as determined by protein A ELISA were below 50 ppm, and endotoxinlevels as determined by the LAL (Limulus Amoebocyte Lysate) chromogenicendotoxin assay were below 0.5 EU/mg.

Example 5 Affinity Maturation of YW71.22

To improve the affinity of anti-Robo4 antibody YW71.22, three phagedisplay libraries were generated in the background of YW71.22, eachtargeting multiple HVRs for soft randomization mutagenesis as describedin Lee et al., J. Mol. Biol. 340(5):1073-93 (2004). To avoidre-selecting YW71.22 from a potential high background of template, stopcodons were introduced into the HVR to be mutated prior to generatingeach library. A solution sorting method was used to enhance theefficiency of the affinity-based phage selection process. Bymanipulating the biotinylated target concentration, reducing the phagecapture time to lower backgrounds and the addition of unbiotinylatedtarget to eliminate clones with faster off rates, high affinity clonescan be proficiently selected. Lee et al., J. Mol. Biol. (2004), 340(5):1073-93. From the first round of selection, enrichment (target dependentphage capture) was observed suggesting a large number of clones werepresent in each library with reasonably high affinity for human Robo4.Selection stringency was increased in subsequent rounds. After 5 roundsof selection, clones from each library were analyzed. New sequences wereobserved in libraries targeting each of the six HVRs (FIGS. 2A and 2B).Selected clones were screened by phage ELISA and then expressed as IgGprotein and their affinity characterized using Biacore™ bindinganalysis.

Phage libraries of affinity matured clones were sorted using asolid/solution sorting method. Human Robo4-His was biotinylated bymixing 500 μl of 3.6 mg/ml human Robo4-His in PBS, and 10 μl of 1 Mpotassium phosphate, pH 8 with 20 μl 4 mM Sulfo-NHS-LC-biotin (Pierce).For the first round of selection, biotinylated Robo4-His was coated onMaxiSorp microtiter plates (Nunc) at 10 μg/ml in PBS and incubatedovernight at 4° C. For the first round of selection 16 wells of targetwere used. Wells were blocked for 1 hour at room temperature usingSuperBlock (Pierce). Maturation phage libries were diluted in SuperBlockbuffer and incubated 1 hour at room temperature. Phage libraries werethen added to the blocked antigen plates incubated 2 hours at roomtemperature. After binding, unbound and non-specifically bound phagewere removed from the antigen plates by washing with Wash Buffer (PBS,05% Tween®20). Bound phage were eluted by incubating the wells with 50mM HCl, 0.5 M KCl for 30 min. Phage were amplified using XL-1 Blue cellsand M13/KO7 helper phage and grown for 36 hours at 30° C. in 2YT, 50μg/ml carbanecillin, 50 ug/ml kanamycin, 10 μg/ml tetracycline.Amplified phage were then recovered using a modified PEG precipitationprotocol (Clackson & Lowman 2004). The titers of phage eluted from atarget coated well were compared to titers of phage recovered from anon-target coated well to assess enrichment. For selection rounds 2-5 asolution sorting protocol was implemented. Microtiter wells were coatedwith 10 μg/ml neutravidin in PBS overnight at 4° C. and then blocked for1 hour using SuperBlock (Pierce). Recovered phage libraries weresuspended in SuperBlock and were mixed with 50 nM biotinylated Robo4-Hisfor 1 hour. Phage bound to biotinylated Robo4-His were captured onneutravidin coated wells for 30 min and unbound phage were washed awaywith Wash Buffer. Phage were eluted using 50 mM HCl, 500 mM KCl for 30min, neutralized, and propagated in XL1 blue cells (Stratagene) in thepresence of KO7 helper phage (New England Biolabs). Subsequent rounds ofsorting were performed similarly with the following exceptions: in round2 the final biotinylated Robo4-His concentration was 50 nM, in round 3the final biotinylated Robo4-His concentration was 25 nM, in round 4 thefinal biotinylated Robo4-His concentration was 5 nM and in round 5 thefinal biotinylated Robo4-His concentration was 0.5 nM with 50 nMunbiotinylated Robo4-His added to the mixture for 1 hour prior tocapture on neutravidin.

Several affinity matured clones were selected for binding to humanRobo4-His and sequenced. The variable region sequences of the antibodyclones derived by affinity maturation of clone YW71.22 are shown in FIG.2A (light chain variable regions) and FIG. 2B (heavy chain variableregion).

Example 6 Characterization of Selected Anti-Robo4 Antibody Clones

Phage ELISA—Phage competition binding assays were performed to determinethe approximate binding affinity (determined as phage IC₅₀) ofphage-displayed Fabs for Robo4. The assays were performed as follows.Briefly, purified phage supernatants from each clone were produced usinga modified PEG precipitation protocol as described above. Purified phagesupernatants were serially diluted in Phage Blocking buffer, thenincubated on plates coated with Robo4-His (1 μg/ml) for 15 minutes. Theplates were washed with Wash Buffer and were incubated for 30 minuteswith horseradish peroxidase/anti-M13 antibody conjugate (diluted 1:5000in PBS buffer) (Amersham Pharmacia Biotech). The plates were washed,developed with tetramethylbenzidine (TMB) substrate (Kirkegaard andPerry Laboratories) and quenched with 0.1NH₂SO₄. Absorbance was measuredspectrophotometrically at 450 nm to determine the phage concentrationgiving about 50% of the signal at saturation. A fixed, sub-saturatingconcentration of phage was diluted in Phage Blocking buffer containingtwo-fold serial dilutions of Robo4-His protein from 350 nM Robo4 to 5 nMRobo4. The mixtures were incubated for one hour with gentle shaking atroom temperature, transferred to plates coated with Robo4-His (1 μg/ml)and the plates were incubated for 20 minutes. The plates were washed andtreated as above. The binding affinities were estimated as IC₅₀ values(defined as the concentration of antigen that blocked 50% of the phagebinding to the immobilized antigen). The IC₅₀ results for the sevenclones are shown in Table 2.

TABLE 2 Anti-Robo4 Phage Competition Summary Phage IC₅₀ Clone versushuman Robo4 YW71.6 15 nM YW71.22  5 nM YW71.1 15 nM YW71.89 20 nM YW79.115 nM YW79.11 <5 nM YW79.8 <5 nM

Fab Production and Affinity Determination—To express Fab protein foraffinity measurements, a stop codon was introduced between the heavychain and g3 in the phage display vector. Clones were transformed intoE. coli 34B8 cells and grown in AP5 media at 30 C (Presta et al. CancerRes. 57: 4593-4599 (1997)). Cells were harvested by centrifugation,suspended in 10 mM Tris, 1 mM EDTA pH 8 and broken open using amicrofluidizer. Fab was purified with Protein G affinity chromatography.

Affinity determinations were performed by surface plasmon resonanceusing a BIAcore™ 2000 system (BIAcore, Piscataway, N.J.). Robo4-His wasimmobilized (˜1000 response units (RU)) on a CM5 chip and variedconcentrations of Fab (4 to 500 nM) in PBST were injected. After eachinjection the chip was regenerated using 100 mM HCl.

The binding affinity of three phage-derived anti-Robo4 antibodies forsoluble Robo4 extracellular domain (ECD) was determined by surfaceplasmon resonance measurement using a BIACORE® 3000 system (Biacore,Inc., Piscataway, N.J.). The antibodies tested included YW71.6, YW71.22,and YW79.8. Briefly, carboxymethylated dextran biosensor chips (CM5,Biacore Inc.) were activated withN-ethyl-N′-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC) andN-hydroxysuccinimide (NHS) according to the supplier's instructions.These activated chips were coated with anti-Robo Fab by dilution to 5ug/ml with 10 mM sodium acetate, pH 4.8, before injection at a flow rateof 5 μl/minute to achieve approximately 500 response units (RU) ofcoupled antibody. Next, 1M ethanolamine was injected to block unreactedgroups. For kinetics measurements, two-fold serial dilutions of human ormouse-ECD-His tagged soluble antigen (approximately 500 nM toapproximately 7.8 nM) were injected in PBS with 0.05% Tween® 20 at 25°C. at a flow rate of 25 μl/min. Binding response was corrected bysubtracting the RU from a blank flow cell. Association rates (k_(on))and dissociation rates (k_(off)) were calculated using a simpleone-to-one Langmuir binding model (BIAevaluation Software version 3.2).The equilibrium dissociation constant (K_(D)) was calculated as theratio k_(dissociation)/k_(association). The results of this experimentare shown in Table 3 below. Antibody YW71.22 cross-reacts with human andmouse Robo4.

TABLE 3 Anti-Robo4 BIAcore ™ Binding Analysis Summary Clone ka kd K_(D)Human Robo4 YW71.22 2.90E+05 3.70E−03 1.30E−08 Murine Robo4 YW71.224.50E+05 2.80E−03 6.20E−09

An affinity matured anti-Robo4 antibody clone derived from YW71.22 weretested for binding to human Robo4 expressed endogenously in HUVEC cellsand to murine Robo4 expressed endogenously in MS1 cells. A FACS analysisrevealed that clones YW71.22.S1.16 and YW71.22.S1.21 bound to both humanand murine Robo4 and that binding was comparable to the YW71.22 antibody(FIG. 18).

Example 7 Binding Analysis of Affinity Matured Robo4 Antibodies

Affinity matured YW71.22.S1.16 was used to generate a full-length IgG1and a Fab fragment both with a Cys substitution at position 118 of theheavy chain Fc region according to EU numbering. The Cys is used forsite specific conjugation of the antibody to a label or drug ofinterest.

Binding affinities to human and mouse Robo4 were determined by in vitrobinding measurements and by radiolabeled cell binding for full-lengthYW71.22.S1.16 (Mab), full-length YW71.22.S1.16 with engineered Cys(thioMab), and a Fab fragment of YW71.22.S1.16 with engineered Cys(ThioFab).

The in vitro binding experiments were performed by SPR measurements on aProteOn XPR36 instrument (Bio-Rad Laboratories, Inc.) at 25° C. Affinitymatured Robo4 antibodies (Mab, ThioMab and ThioFab) were immobilized atsurface densities of 500-1000 RUs on an activated ProteOn GLC sensorchip (Bio-Rad Laboratories, Inc.) using standard amine couplingprocedures as described by the manufacturer. Briefly, antibodies wereinjected at a concentration of 10 μg/ml in 20 mM sodium acetate, pH 4.5and at a flow rate of 30 μl/min for 5 min. Unreacted groups were blockedby injecting 1 M ethanolamine. To perform binding assays, samples wereinjected at a flow rate of 30 μl/min. For kinetics measurements serialdilutions of either purified human or mouse Robo4-His (approximately 25nM to 0.8 nM) were injected in PBS with 0.01% Tween-20 and sensorgramsfor association and dissociation phases were recorded. Blank surfaceswere used for background corrections. There was no need to regeneratesurfaces since the ProteOn protein interaction array system allows torun up to six binding experiments on an identical surface in parallel.Association rates (k_(a)) and dissociation rates (k_(d)) were calculatedusing a simple one-to-one Longmuir binding model (ProteOn ManagerSoftware V2.0, Bio-Rad Laboratories, Inc.) and the equilibriumdissociation constant (K_(D)) was calculated as the ration k_(d)/k_(a).The results are summarized in Table 4 below.

TABLE 4 Anti-Robo4 Antibody Affinities (K_(D)) Summary Antibody formatIn vitro (SPR) Radiolabeled Cell Binding (YW71.22.S1.16) hRobo4 mRobo4HUVEC MS1 thioMAb 1.2E−09 1.1E−09 1.2E−09 1.0E−09 MAb 1.1E−09 0.9E−09 NDND thioFab 8.0E−09 1.5E−09 ND 3.2E−09

HUVECs and MS1 cells, which endogenously express Robo4 protein were usedin radioligand cell binding experiments.

For the cell binding experiments anti-Robo4 thioMab and thioFabantibodies were iodinated using the Iodogen method. Each radiolabeledantibody was purified from free ¹²⁵I—Na by gel filtration using a NAP-5column; the purified thioMab antibody had a specific activity of 6.96μCi/μg and the purified thioFab antibody had a specific activity of16.05 μCi/μg. 50 μL competition mixtures containing a fixedconcentration of iodinated antibody and decreasing concentrations of theunlabeled antibody were placed into 96-well plates. MS1 and HUVEC cellswere cultured in growth media at 37° C. in 5% CO₂ and then were detachedfrom tissue culture plates using a non-enzymatic cell dissociatingsolution (Sigma #C5914) for subsequent binding studies. Cells werewashed with binding buffer (50:50 DMEM/F12 media containing 2% FBS, 2 mMsodium azide and 50 mM HEPES, pH 7.2) and were placed into the 96-wellplates containing the competition mixtures at approximately 200,000cells in 0.2 mL of binding buffer. The final concentration of theiodinated Mab antibody in each incubation with cells was ˜150 pM(˜70,000 cpms per 0.25 ml) and the final concentration of the unlabeledantibody in the incubations with cells started at 400 nM and wasserially diluted by 2 fold for 10 concentrations. The finalconcentration of the iodinated Fab antibody in each incubation withcells was ˜400 pM (˜150,000 cpms per 0.25 ml) and the finalconcentration of the unlabeled antibody in the incubations with cellsstarted at 1.0 uM and was serially diluted by 2 fold for 10concentrations. Competition reactions were assayed in triplicate. Thecompetition reactions were incubated for 2 hours at room temperature.Then they were transferred to a Millipore Multiscreen filter plate andwashed three times with binding buffer to separate the free from boundiodinated antibody. The filters were counted on a Wallac Wizard 1470gamma counter (PerkinElmer Life and Analytical Sciences Inc. Wellesley,Mass.). The binding data was evaluated using NewLigand software(Genentech), which uses the fitting algorithm of Munson and Robard,Anal. Biochem. 107: 220-39 (1980), to determine the binding affinity ofthe antibody and the concentration of binding sites per well. The numberof binding sites per cell was determined by dividing the total bindingsites by the number of cells per well.

Example 8 Anti-Robo4 Antibody Inhibits HUVEC Tube Elongation

Anti-Robo4 antibody (YW71.22) significantly inhibits HUVEC tubeelongation in a bead outgrowth assay. Both total number and length ofthe tubes are reduced as compared to the control antibody E25 (FIG. 20).For example the number of tubes with a length of 300 μm or more isreduced by 60%.

For the bead outgrowth assay, dextran-coated Cytodex 3 microcarrierbeads (Amersham) were incubated with HUVECs (400 cells per bead) inEGM-2, overnight at 37° C. and 5% CO₂. To induce clotting, 0.5 mlcell-coated beads in PBS with 2.5 μg/ml fibrinogen (200 beads/ml) wasadded into one well of a 24-well tissue culture plate containing 0.625units thrombin and incubated for 5 min at room temperature and then for20 min at 37° C. The clot was equilibrated in EGM-2 for 30 min at 37° C.The medium was then replaced with EGM-2 containing skin fibroblast cells(Detroit 551, 20,000 cells/ml). Antibodies (50 μg/ml) were added to eachwell, and the assay was monitored for 8 days with change in medium everyalternate day. Images of the beads were captured by an invertedmicroscope, and concentric circles spaced at 100, 200, and 300 μm weredrawn around the bead in each image. The number of vessels crossing eachcircle was counted 10-12 beads were used per condition forquantification (Nakatsu et al., Microvascular Research 66: 102-112(2003)).

Example 9 Anti-Robo4 Antibody and Anti-Robo4 Antibody Drug Conjugates asTherapeutics

Anti-Robo4 ADCs were produced by conjugating anti-Robo4 antibodies tothe drug-linker moieties MCC-DM1, SPDB-DM4, and mPEO-DM1. Prior toconjugation, the antibodies were partially reduced with TCEP usingstandard methods in accordance with the methodology described in WO2004/010957. The partially reduced antibodies were conjugated to theabove drug-linker moieties using standard methods in accordance with themethodology described in Doronina et al., Nat. Biotechnol. 21:778-784(2003) and U.S. Patent Application No. 2005/0238649. Briefly, thepartially reduced antibodies were combined with the drug linker moietiesto allow conjugation of the moieties to cysteine residues (includingwithout limitation, cysteine engineered residues of thioMAbs asdisclosed herein). The conjugation reactions were quenched, and the ADCswere purified. The drug load (average number of drug moieties perantibody) for each ADC was determined by HPLC. Additional anti-Robo4ADCs are made using e.g., drug linker moieties including spp-DM1,smcc-DM1, MC-vc-PAB-MMAE; MC-vc-PAB-MMAF; MC-MMAE and MC-MMAF (see,e.g., WO 2004/010957, and WO2006/034488 (each of which is hereinincorporated by reference in its entirety).

Example 10 In Vivo Tumor Volume Reduction Assay

Naked anti-Robo4 antibody: Tumor growth was not inhibited by nakedanti-Robo4 antibody YW71.22 (antibody not conjugated to a cytotoxicagent or other agent) in mouse xenograft models of human non-small celllung carcinoma SK-MES-1. For this study, each HRLN female nude mousereceived a 1 mm³ tumor fragment s.c. implant in the flank. Tumor growthwas monitored twice weekly by caliper measurements. When tumors reachedan average size of 80-120 mm³, mice were sorted to give nearly identicalgroup mean tumor sizes, and treatment was started (Day 1). Animals weredosed twice weekly i.p. with 10 mg/kg anti-Robo4 and/or 5 mg/kganti-VEGF or control antibody for 5 weeks. All treatments were bodyweight-adjusted at 0.2 mg/20 g. The results are shown in FIG. 17. Inaddition, no reduction of tumor growth in Fo5 mouse model withMDA-MB-231 breast cancer xenograft was observed.

An anti-Robo4 antibody comprising an Fc region having enhanced ADCCactivity may be used to inhibit tumor growth. The ADCC-enhancedanti-Robo4 antibody may be a naked antibody or an antibody drugconjugate as disclosed herein. ADCC enhancement is achieved, forexample, by enhancing IgG1-FcgammaRIII interactions, which are dependenton the carbohydrate moieties linked to the antibody Fc region.Non-limiting exemplary methods for ADCC enhancement include reducingantibody fucosylation by expressing anti-Robo4 in a host celloverexpressing GnTIII, which encodes N-acetylglucosaminyltransferase(Narishimhan, J. Biol. Chem. 257:10235-10242 (1982) and Umana et al.,Nature Biotech. 17:176-180 (1999)); a host cell underexpressing orlacking expression of FUT8, which encodes alpha-1,6-fucosyltransferase(Shinkawa et al., J. Biol. Chem. 278:3466-3473 (2003)); or a host celllacking or underexpressing UDP-N-acetylglucosamine 2-epinerase (such asLec3 CHO cells) (Hong and Stanley, J. Biol. Chem. 278:53045-53054(2003)). In addition, ADCC is enhanced by amino acid changes in the Fcregion (see for example WO2000042072 and WO2004029207). Thus, anti-Robo4antibodies of the invention are useful as cytotoxic agents includeanti-Robo4 antibodies exhibiting enhanced ADCC function relative to ananti-Robo4 antibody exhibiting wild type Fc ADCC activity.

Anti-Robo4 antibody drug conjugate (Anti-Robo4 ADC): To test theefficacy of toxin-conjugated anti-Robo4 ADCs for the ability to reducetumor volume in vivo, the following protocol is employed.

SCID mice are each inoculated subcutaneously in the flank with cells ofa human cancer cell line. The human cancer cell lines include, asnon-limiting examples, SK-MES-1 human non-small lung cancer cells andMDA-MB-231 breast cancer cells. When the tumors reach a mean tumorvolume of between approximately 80-200 mm³, the mice are divided intogroups, and treated by intravenous injection with toxin-conjugatedantibody or unconjugated antibody.

Use of a Anti-Robo4 Maytansine Drug Conjugates to Reduce Solid TumorVolume

SCID mice are injected with human tumor cells subcutaneously in a volumeof 0.2 ml/20 g mouse body weight in the flank. Cells are suspended inHBSS. When the mean tumor size reaches approximately 80-200 mm³, miceare randomly grouped into groups and given a single or multiple I.V.treatments (via the tail vein) of either a anti-Robo4 ADC conjugated tomaytansine or a control antibody.

Mean tumor volume is monitored in each treatment group for approximately30 days post-antibody injection. Tumor may be detected by, for example,fluorescence detection of remaining luciferase where the tumor cells areengineered to express luciferase. Efficacy of the toxin-conjugatedanti-CD22 antibodies is determined by comparison to control andunconjugated antibodies.

The same experiment is performed using anti-Robo4 ADC wherein the drugconjugated to the antibody is an auristatin.

The same experiment is repeated using an anti-Robo4 ADC comprising an Fcregion having enhanced ADCC activity.

Example 11 Anti-Robo4 Antibodies Conjugated to Detectable Markers

sDOTA-labeled anti-Robo4 antibodies are prepared as follows. TheDOTA-NHS-ester was dissolved in dimethylacetamide (DMA, Fluka Chemika,Switzerland) and prepared to concentrations of 60-100 mg/mL. Typicalprocedures involved buffer exchanging the MAb into PBS with 2 mM EDTA atpH 7.2. Reactions were performed at a ratio of 1 molecule MAb to 4 DOTAmolecules (1:4) and carried out at 25° C. while gently stirring on aThermomixer plate (Eppendorf, Westbury, N.Y.). The DOTA-labeledanti-Robo4 antibody is useful as a detectable marker in vitro or in vivowhen associated with, as non-limiting examples, yttrium ⁹⁰Y, ¹¹¹In,¹⁷⁷Lu and the like. The mAb conjugates are labeled with, for example,¹¹¹In by incubating the conjugate with ¹¹¹InCl₃ in 0.25 M ammoniumacetate for 45 min at 43° C. EDTA is added to a final concentration of 1mM, and the mixture is incubated at 37° C. for 15 minutes. Labeling with⁹⁰Y, for example, is performed using a one-hour incubation at 43° C.,after which DTPA is added to a final concentration of 1 mM, and themixture is incubated for an additional 15 min at 37° C. Theradiometal-labeled mAb conjugates are purified by size exclusion HPLC,using a TosoHaas TSKgel G2000 SW column and a mobile phase of normalsaline.

Example 12 Additional Characterization of Robo4 and Anti-Robo4Antibodies

Robo4 does not block endothelial cell (EC) migration. Robo4-Fc andRobo4-His were contacted with vascular ECs using a HUVEC migration assayand in the presence or absence of VEGF. FIG. 8 shows the results of theassay. Robo4-Fc or Robo4-His alone did not induce EC migration andVEGF-induced EC migration was not enhanced by Robo4.

Robo4 does not bind to Slit2. Robo4-Fc contacted with Slit2 did not showbinding by Biocore™ analysis, whereas Robo1 and Slit 2 did show bindingin the same assay (FIG. 9). Slit2-His (histidine-tagged full-lengthSlit2) was immobilized on a CM5 Biacore™ chip at high density. A 5 μlaliquot of each analyte (Robo4-Fc or Robo1-Fc fusion proteins) wasinjected and allowed to interact with the immobilized ligand in buffer(HEPES/EDTA/NaCl, pH7.5).

Robo4 interacts in vitro with UNC5B, a cell surface receptor involved invascular guidance. It has been shown that netrin binding to members ofthe uncoordinated-5 (UNC5) family of receptors (UNC5A, B, C, and D)results in neural axon repression (Klagsbrun, M. and Eichmann, A.,Cytokine & Growth Factor Reviews 16(4-5):535-548 (2005)). Netrin-UNC5Binteraction has been implicated in angiogenesis (Klagsbrun, M. andEichmann, A., supra (2005) and Lu, X. et al., Nature 432:179-186(2004)). The interaction of Robo4 with UNC5B in vitro was determined bySPR binding measurements in which UNC5B-Fc fusion protein (extracellulardomain of UNC5B fused to an Fc region) was immobilized on a chip andsoluble Robo4-Fc or Robo4-His was allowed to interact with it atdifferent concentrations. SPR measurements were performed as describedin Example 7 and the interaction results are shown in FIG. 10.

Robo4 is expressed in fetal mouse endothelium as shown by an ISH assayusing Robo4 specific RNA probes (FIG. 11). Robo4 is also expressed inmouse tumor models of colon tumor (human HM-7 colon tumor xenograft,FIGS. 12A and 12B) and in mammary tumor (human MDA-MB-175 breast cancertumor xenograft, FIGS. 12C and 12D). Robo4 shows increased expression inhuman tumor tissue relative to normal human tissue as evidenced in FIGS.13A and 13C (increased expression in malignant melanoma) relative tonormal tissue (FIGS. 13B and 13D). Robo4 expression is also seen inhuman small cell lung cancer (FIGS. 14A-D), human colon cancer (FIGS.14G-H), human prostate tumor, and mouse angiosarcoma. Robo4 is expressedin tumor endothelial cells in colon, non-small cell lung cancer, renalcell carcinoma (RCC), transitional cell carcinoma (TCC, a common form ofbladder cancer), breast cancer, glioma, and sarcoma.

Anti-Robo4 antibody YW71.22 was internalized by Robo4-expressing mousemicrovascular endothelial MS1 cells over a period of 2 hours. TheYW71.22 antibody was allowed to bind Robo4 on mouse microvasculatureendothelial MS1 cells at 0° C. for 30 minutes, incubated at 37° C. for0-2 hours. At intervals, cells were fixed and permeabilized or notpermeabilized. Anti-Robo4 antibodies on the cell surface or internalizedby the cell were interacted with a fluorescently labeled (Alexa-labeled)anti-human IgG secondary antibody. The results are shown in FIGS. 15Aand 15B. The YW71.22.S1.16 anti-Robo4 antibody was internalized by thesame protocol except that anti-Robo4 was incubated on MS1 cells at 37°C. was for 0-4 hours. Cells were permeabilized and stained as above. Theresults are shown in FIG. 15C.

Endothelial cell migration was not blocked by anti-Robo4 antibody in anin vitro assay using human umbilical vascular endothelial cells (HUVEC)cellular migration assay. HUVECs endogenously express human Robo4. Theassay was performed as follows. HUVECs were pre-incubated for 2 hourswith VEGF. Cellular migration was allowed to continue for 16 hours inthe presence of anti-Robo4 antibody YW71.22, anti-VEGF antibody, orRobo4-Fc or Robo4-His. Neither anti-Robo4 nor the soluble Robo4extracellular domain fusion proteins (Robo4-Fc and Robo4-His) blocked ECmigration under these conditions (FIG. 16).

Anti-Robo4 antibody associates with vasculature in vivo. Fiftymicrograms of anti-Robo4 antibody 71.22 (FIG. 19A) or control antibody(anti-HER2, FIG. 19B) were injected via tail vein and allowed tocirculate for 10 minutes. One hundred micrograms of FITC-Lycopersicumesculentum was injected and allowed to circulate for 5 minutes. Micewere perfused with 1% PFA in PBS, tissues were collected into 30%sucrose and frozen in OCT. Antibodies were detected with Cy3 goatanti-human IgG. FIG. 19A shows that the location of FITC-Lycopersicumesculentum staining in vasculature overlaps with the location ofanti-Robo4 Cy3 staining, unlike the control antibody which migrated intosurrounding tissue.

Although the foregoing invention has been described in some detail byway of illustration and example for purposes of clarity ofunderstanding, the descriptions and examples should not be construed aslimiting the scope of the invention. The disclosures of all patents,patent applications, scientific references, and Genbank Accession Nos.cited herein are expressly incorporated by reference in their entiretyfor all purposes as if each patent, patent application, scientificreference, and Genbank Accession No. were specifically and individuallyincorporated by reference.

1-24. (canceled)
 25. A method of in vivo imaging, the method, the methodcomprising administering an to a mammal an isolated Robo4 antibodycomprising (i) HVR-L1 comprising SEQ ID NO:1; (ii) HVR-L2 comprising SEQID NO:2; (iii) HVR-L3 comprising SEQ ID NO:3; (iv) HVR-H1 comprising SEQID NO:17; (v) HVR-H2 comprising SEQ ID NO:18; and (vi) HVR-H3 comprisingSEQ ID NO:19.
 26. The method of claim 25, wherein the mammal is a human.27. The method of claim 25, wherein the mammal is suspected of having adisease or disorder selected from the group consisting of: cancer,atherosclerosis, retrolental fibroplasia, hemangiomas, chronicinflammation, intraocular neovascular diseases, proliferativeretinopathies, diabetic retinopathy, age-related macular degeneration(AMD), neovascular glaucoma, immune rejection of transplanted cornealtissue, rheumatoid arthritis, psoriasis, and combinations thereof. 28.The method of claim 25, wherein the antibody comprises a light chainvariable domain comprising an amino acid sequence selected from thegroup consisting of: SEQ ID NOS:72-97 as shown in FIGS. 1A and 2A. 29.The method of claim 25, wherein the antibody comprises a heavy chainvariable domain comprising an amino acid sequence selected from thegroup consisting of: SEQ ID NOS:140-165 as shown in FIGS. 1B and 2B. 30.The method of claim 25, wherein the antibody comprises a light chainvariable domain comprising an HVR-L1 comprising SEQ ID NO:1, an HVR-L2comprising SEQ ID NO:2, and an HVR-L3 comprising SEQ ID NO:20.
 31. Themethod of claim 25, wherein the antibody comprises a heavy chainvariable domain comprising an HVR-H1 comprising SEQ ID NO:17, an HVR-H2comprising SEQ ID NO:18, and an HVR-H3 comprising SEQ ID NO:19.
 32. Themethod of claim 25, wherein the antibody comprises (i) a light chainvariable domain comprising an HVR-L1 comprising SEQ ID NO:1, an HVR-L2comprising SEQ ID NO:2, and an HVR-L3 comprising QQSRSDHPT (SEQ IDNO:20); and (ii) a heavy chain variable domain comprising an HVR-H1comprising SEQ ID NO:17, an HVR-H2 comprising SEQ ID NO:18, and anHVR-H3 comprising SEQ ID NO:19.
 33. The method of claim 25, wherein theantibody is selected from the group consisting of a Fab, a Fab′, and a(Fab′)₂.
 34. The method of claim 25, wherein the antibody furthercomprises a detectable label.
 35. The method of claim 34, wherein thedetectable label is selected from the group consisting of: biotin, afluorescent dye, a radionuclide, chelating agent 1, 4, 7,10-tetraazacyclododecane-N,N′, N″, N′″-tetraacetic acid (DOTA), amicrobubble, a perfluorocarbon nanoparticle emulsion, a metallicparticle, and combinations thereof.
 36. The antibody of claim 34,wherein the detectable label is covalently attached to the antibody at acysteine residue.
 37. The antibody of claim 36, wherein the cysteineresidue is at position 118 of the heavy chain Fc region according to EUnumbering.